# Surface agitation & co2 high tech tank



## Bodul67 (Feb 17, 2021)

Good morning all. I have a 55gal deep substrate dirted tank with 3" sand capping with a 20gal sump filter. I have CO2 injection. I have a wave maker above diffuser to disperse co2 and on the other side of tank is another wave maker to circulate co2. This circulation does make a shimmering surface agitation. My question is should there be more agitation or no agitation for the o2/co2 balance. I've read so many websites & forums that for my size tank yes I should have more and some say no agitation. At the moment I can't get any pearling on plants. So confused.


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## mistergreen (Mar 3, 2007)

Your plants look great. Lack of pearling doesn't mean your plants aren't growing as you can see.

You can use a drop checker to see how much CO2 is in your tank or roughly get an estimate by taking the pH before CO2 and pH 4 hours into the CO2 and then use this formula to get the CO2.
CO2(ppm) = 3 * 10^(pH2-pH1)

A sump might be your trouble where the CO2 is degassing. Do you need a sump? Also, cover the sump will help.


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## Hank Junior (Oct 1, 2020)

Bodul67 said:


> Good morning all. I have a 55gal deep substrate dirted tank with 3" sand capping with a 20gal sump filter. I have CO2 injection. I have a wave maker above diffuser to disperse co2 and on the other side of tank is another wave maker to circulate co2. This circulation does make a shimmering surface agitation. My question is should there be more agitation or no agitation for the o2/co2 balance. I've read so many websites & forums that for my size tank yes I should have more and some say no agitation. At the moment I can't get any pearling on plants. So confused.


I used to have injected CO2 but am finding my CO2 injection increasingly redundant. I presently only have one tank with CO2 but I mostly leave it switched off - its my hospital tank, an intensive care unit for plants that look like they are about to die - I hate to lose a plant.

The interface between water and air is simple - it adds gases to your water and removes gases from your water. If you are lacking CO2 you should agitate the water/clean the surface from biofilm and your water will naturally increase its CO2 content. If you have an excess of CO2 (a very unlikely scenario!) it will remove the excess. A tank full of plants will create a CO2 deprived aquaria very quickly unless this gas interchange is properly maintained.

The common belief that water agitation drives out CO2 and increases dissolved O2 is not strictly true. It normalises ALL GASES not just O2. Agitating water will normally increase BOTH O2 and CO2 levels in an aquarium. Alternatively install an Air Pump - yes an air pump! It will help increase your dissolved CO2 and O2.

How did I discover this secret? The hard way I can assure you.


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## mistergreen (Mar 3, 2007)

Hank Junior said:


> The common belief that water agitation drives out CO2 and increases dissolved O2 is not strictly true. It normalises ALL GASES not just O2. Agitating water will normally increase BOTH O2 and CO2 levels in an aquarium. Alternatively install an Air Pump - yes an air pump! It will help increase your dissolved CO2 and O2.


Yes, this is true but CO2 will only be 2-3ppm by weight in the water. That's good for low-light plants but not good for high-light plants which require more CO2 for growth and color.


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## Hank Junior (Oct 1, 2020)

mistergreen I respectfully disagree. I have a planted tank with a supposedly high-CO2 consuming plant (lileopsis brasil and brisbanica) which is pearling without CO2 injection for about 4 months now - I switched the CO2 injection off 4 months ago. Yesterday I discovered why. Its not nutrients or my water it is simply dissolved atmospheric CO2.

Pearling is about 30-60% what I got with CO2 injection and usually at the end of the light period. Lileopsis is a high light plant - hence why I get alot of green water, but it does grow as well as it did before. My green water problem is I am pretty sure a result of daily liquid fertilisers - my soil experiments are not presently working for me.

I have other plant tanks with no pearling and healthy plants but the light level is lower.

This whole high light/high CO2 requirement is where I disagree with Walstad - but her book is my aquaria bible in every other respect. I don't believe in 'shade plants'. Shade to a plant = death imo... All plants require light and lots of it. As aquarists we have convinced ourselves that light is the problem simply because we have algae problems. The problem lies elsewhere.


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## Hank Junior (Oct 1, 2020)

To give you an idea of what I am talking about - about 4 months ago I had a beautiful plant tank in pond mud which was thriving. Its a native plant I took out of a dam complete with mud and dam water - some sort of aquatic grass. Didn't need fertiliser - needed nothing except topping up evaporation with rain water and LED lighting. I had to go away for 2 weeks and left the LED lights on a timer - put a glass lid (the usual aquarium lid with holes/cut outs in it) on it to reduce evaporation while I was away. Had this tank for about 3 months before I left on my trip. Prior to my trip it had no lid on it but was open to the air.

When I returned all the plants were dead including the micro-fauna and it was just pond mud. Either the lid killed the plants, too little gas exchange, OR a biofilm formed on the surface of the water and did the same job.

I don't keep lids on any of my plant tanks any longer. Incidentally this little native grass in pond mud was pearling like crazy under artificial LED lighting a few bubbles every second - no CO2 injection required.

EDIT- something I have noticed about pond mud is that often surface algae living on the mud generates alot of O2. Part of the bubbling may have been algae not just the grass, but I know the grass was pearling as it was growing like a weed. This algae/pond mud gas bubbles that look just like pearling had me scratching my head for months. At first I thought it was some sort of CO2 generation going on - decomposition/ methane gas - which probably does occur in the pond where I took ut from. I am pretty sure now after much experimentation with pond mud that it is actually algae and O2, not CO2 being generated in my aquaria where I use pond mud.


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## zahtar (Sep 29, 2019)

*Bodul67,* I would go with measuring as mistergreen suggested. Any of two ways is easy to go with (drop checker or ph measurement). By the way, I have been using a different formula that takes kH into account in relation to ph in order to estimate CO2 concentration. By measuring you can take note of the values on a spreadsheet and see how they do long term.

*Hank Junior, *if U understand correctly, you suggest pearling to be a measure of how well plants are doing. Is this what you mean? Additionally, you mentioned that you do not believe in "shade plants" and that the algae problem lies elsewhere.


Hank Junior said:


> ... I don't believe in 'shade plants' ... All plants require light and lots of it. As aquarists we have convinced ourselves that light is the problem simply because we have algae problems. The problem lies elsewhere.


So what would you advise to a new hobbyist to keep as a routine in order to avoid algae problems?

I am always trying to understand different approaches and how people get similar results in different ways.

Thanks in advance


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## Hank Junior (Oct 1, 2020)

Guys just to explain - I lurk on this forum but try not to contribute too much for the simple reason that I intend to write a book about growing aquarium plants - need to keep something for my book. I have a very different approach to plants - more akin to yesteryear than modern - I have just started making my own plant compost (terrestrial plants not aquatic) to use as a fertiliser for example - but composting takes time - a long time. Presently to speed things up I have just started to experiment with soil from an orange orchard which is irrigated by the outflow of a septic tank (yes human sewerage processed by soil bacteria) to try to address the nutrient-deficient muds I presently am using - hence why I still use liquid fertilisers. This soil has been processing nutrients for years and is very rich in vegetable plant matter - almost black. Incidentally sewerage outflow water is seriously being considered now for agricultural farm production. As you can imagine sewerage contains alot of nutrients and the orchard is doing very very well. Never needs fertilisers.

Walstad method is the best approach presently to growing aquarium plants imo. Not to say you can't get fantastic results like Amano did with high tech but I feel that the whole water plant thing is not working for 99% of people. When I say not working I mean many many problems. Let me use my present 20L tank as an example (the problem tank, I have about 15 tanks of various sizes, most are very small).


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## mistergreen (Mar 3, 2007)

Hank Junior said:


> mistergreen I respectfully disagree. I have a planted tank with a supposedly high-CO2 consuming plant (lileopsis brasil and brisbanica) which is pearling without CO2 injection for about 4 months now - I switched the CO2 injection off 4 months ago. Yesterday I discovered why. Its not nutrients or my water it is simply dissolved atmospheric CO2.


I have the opposite experience. Plants were slow-growing and deformed until I added 15ppm of CO2.


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## Hank Junior (Oct 1, 2020)

After a twenty year absence of growing plants (work and life meant I stopped keeping aquariums) I returned to the hobby last September. Filled a 20L cube tank with potted plants of various sorts using Amano Amazonia 2 soil, Seachem fertilisers and CO2 injection - intending to use these plants for my soil experiments. After 1 month my CO2 failed and to my amazement my plants continued to prosper (except one species which is causing me alot of problems, which is another story - this species is alive but sick looking and needing attention - it is kept elsewhere - pond mud rescued it and kept it alive but only just!).

After about 6 months I noticed a deterioration in the water and micro-fauna (daphnia etc...I have no fish). The water turned green and the daphnia almost dissapeared. Things came to a crisis point yesterday when I think I have only one fresh water prawn like creature (have no idea what these are called but they swim around like little fish). Massive water changes over the past 4 weeks have kept my fauna alive but only barely. Yesterday I solved the problem. I use a combination of river water (PH8 and quite hard) and rain water to soften it and bring down the PH a bit, but I don't measure any water parameters. I tested the source waters at the start (my river water and rain water) but I let the plant pearling be my guide to plant health in this tank, just as I did when I used the CO2 system - lots of pearling my plants are doing well - no pearling I know there is a problem in this tank. Other tanks of mine don't pearl but they are handled differently.


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## Hank Junior (Oct 1, 2020)

My fauna was dying from a film-scum that forms on my tank (my other tanks in sunlight have no problem with a scum layer at all - never need to clean them). Combined with a low photo period of only 5 hours (I use intense LED lighting - almost need sunglasses when looking at my tanks). My 20L typically has from 50W to 20W of LED for 5 hours which is about 5x more light than most people use. (I originally used an older style 150W metal halide floor lamp on this tank until I saw my electricity bill! and switched to LED - the light level in this tank was approaching ambient outside daylight).

Yesterday I cleaned the surface of the water and plants began pearling again like before. Because I change 50% of water once a week and clean the surface at the same time, my tank for a long time has been on a cycle of clean water adequate gases, and partial scum cover deprived gases for weeks now.

A few changes I made were catastrophic. No 1 I removed the Eheim surface cleaner I used to run 10 minutes a day to clean the water surface only cleaning it with water changes. No 2 I increased the tank temperature to 25C from my initial 20C as I seem to get more pearling that way. Problem is higher temperature means less dissolved gases! My water prawns asphyxiate faster! My low light period just made the problem worse - chronic shortage of O2.

I noticed that before I made those changes a month ago my green water was manageable, daphnia were plentiful and water prawns swimming around like crazy. Green water dimishes light penetration which is not good but I also realise now that biofilm reflects light and reduces the light levels too. The bacteria were basically killing my aquarium.

Needless to say I have refitted the Eheim cleaner and will run it 10 minutes a day. Biofilm is the silent killer of aquariums as far as I am concerned. Its enemy number one. Kills plants, kills fauna, kills fish.


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## Hank Junior (Oct 1, 2020)

I realise now that when I was adding my daily liquid fertiliser as usual the past 4 weeks the green water algae was the only thing benefitting as my plants and fauna were gas deprived. Hence the green water problem. Daphnia eat green water algae so when you have a healthy population they keep the water cleaner but they do require some green water or they will die. Now I know in green water without gas exchange they will die as well. I have a few swimming around but nowhere near like I used to.

I can't really suggest a solution for beginners as I am still very much in learning mode myself. I suspect my experiments may take a decade?


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## mistergreen (Mar 3, 2007)

Your natural waters might have naturally dissolved CO2 higher than what's available in the air. It might be fun to try to measure your CO2.
Take a container of your water and microwave it till it boils away all of the CO2. Measure that pH on that and water in your tank.
Use this formula to find the CO2 concentration.
CO2(ppm) = 3 * 10^(pH2-pH1)


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## Hank Junior (Oct 1, 2020)

I can totally understand people for being skeptical about this. I only know this because I have seen it with my own eyes - yesterday when I saw my lileapsis pearl again after cleaning the water surface was a my Conversion moment! I am now a believer in the water-air interface phenomenon and how critical it is to an aquarium. I think that CO2 injection is simply fixing the problem of chronic gas deprivation. The irony is is that in a tank with no plant but only fish (only oxygen consumers) the problem of chronic CO2 shortage doesn't occur. The plants are actually killing themselves! Its funny in a way. We fill our tanks with CO2 consumers and then complain that their is not enough CO2 in our tanks! Of course not, they are consuming it all with gusto my friends.


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## Hank Junior (Oct 1, 2020)

mistergreen said:


> Your natural waters might have naturally dissolved CO2 higher than what's available in the air. It might be fun to try to measure your CO2.
> Take a container of your water and microwave it till it boils away all of the CO2. Measure that pH on that and water in your tank.
> Use this formula to find the CO2 concentration.
> CO2(ppm) = 3 * 10^(pH2-pH1)


Yes good point. Sorry I don't measure water parameters anymore - not enough time in my day. I go by feel and trial and error. Yes for a long time I thought that the river water was the reason. I know now that it isn't. I recently changed my tank from 100% river water to 100% rain water (like it was at the very start) and can confirm that the water changes with rain water produces the pearling as much as the river water. That should have been my clue. Rain water contains almost no nutrients. Only dissolved gases could explain this extra pearling on water change day. About a week ago I settled on 50% rain water and 50% river water as I am not keen on rain water's lack of everything (but gases it seems).

I can only come to one conclusion - water contains more gas than our aquariums!!! Why is this so? That is the question. I think I know the answer now.


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## Hank Junior (Oct 1, 2020)

One of the problems with 'water-change day' is that many times (especially lately with massive 80% water changes to save the prawns) I have dropped the water level to the point were some plants become emersed for about ten minutes. So when you refill the tank you are not surprised with the extra pearling - emersed plants will definetly pearl for about a day without any CO2 injection - I am quite familiar with that aspect of my plants. But the extra pearling I am talking about on water change day are the times when I do a normal water change and do not drop the water level low enough to uncover the plants. Whiich is most of the time. I mention this in case people are wondering if that is the reason.


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## Hank Junior (Oct 1, 2020)

I should mention that though I use the Seachem range I don't use a liquid carbon like excel - I just use their normal range of fertilisers. I do own Excel but have never used it - I plan to use it one day as an experiment. My only source of CO2 is natural except for my hospital tank which does get CO2 injection sometimes to rescue a problem plant. My main problem is Cryptocoryne Tropica - which was once thriving in my orginal tank but is on deaths door now. Seems like the healthier my lilaeopisis looks the sicker my crypts are - hence why I have removed them to the hospital and elsewhere in desperation. I wonder if the lilaeopsis is killing them as I am reading Walsdat's book? For now it is a mystery to me. I have to say that even away from the original tank they are sickly. Its really bizarre. Was once my easiest and most succesful plant - easiest to grow - now it just wants to die! I think if all my plants looked like that I would give up. Fortunately I have had success elsewhere.

The only theory I have about my crypt problem is I read that crypts like an acidic substrate, something Amazonia 2 mix seems to be good at. Maybe my water is too high in PH and too hard? Presently living/alive in pond mud but not looking very happy. Very yellow/brown - very ungreen, but surviving might be a nitrogen problem? No idea.

When I first put my crypts in pond mud to save them they developed black spots on their leaves (looked like the plague- never seen black spots on a leaf before) and I thought it was game-over. A few weeks later they seemed to recover and have been reasonably alive since.


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## Hank Junior (Oct 1, 2020)

OK thanks mistergreen, might give that CO2 measurement formula a try. Don't mean to be disrespectfull - if there's one thing I've learnt the past few months is there is often more than one way to skin a cat so to speak and no-one's method can be discounted.

*Bodul67*, sorry my experiments don't really help you with your present plant pearling problem. Presently only my plants in Amazonia v2 substrate pearl without CO2 injection. Some of my other tanks with plants in various muds/dirts are pretty healthy but do not pearl. Most of my tanks don't pearl at all. Other tanks I have are a bit of a distaster but even those have plants alive but sick looking - not completely dead. Alot of water agitation with CO2 injection is probably not a good idea as it will drive out the CO2 you are pumping in. My CO2 inject tank has no water circulation at all 99% of the time - I just run the surface skimmer 10 minutes a day now to clean the water surface, but I could use this very small pump I expect all the time as the water current is minimal.

Pearling to my mind is a function of the level of photosynthesis - pearling means photosynthesis activity is high and also probably that the dissolved O2 content is high as well, hence the bubbles and why I usually get pearling at the end of a lighting period, but not always - sometimes I get pearling from a water change or from adding liquid fertiliser. Reaction time is usually within a minute.

Therefore no pearling is not necessarily a bad thing - just means slower growth. The reason that my 20L tank HAS TO PEARL for me is because of the extreme level of lighting and liquid fertilisers I use daily on it. When I don't see a few bubbles I get worried. From day one this tank has had very high light intensity. I have an identical smaller version of this tank - same plants, same Amazonia substrate that I set up at the same time as this tank. Originally this smaller tank was pearling just like the bigger tank with the same liquid fertiliser and high light routine. But for a long time now I have kept this smaller tank in an outdoor shed with only direct natural sunlight for 2-3 hours a day, no fertiliser added at all, and it never pearls but is perfectly healthy. I do rarely add some liquid fertiliser to the small one but very rarely - maybe once a month I give it the same dose I used to give it daily. It has a small but healthy population of daphnia and crystal clear water (unlike my big tank which is always a bit green). So there is an example of two healthy plant tanks (no fish), same plants, same set up but different growth rates. ie the smaller tank is growing at a much slower rate but is doing very well.

All this to say that pearling isn't the be-all of plant propogation. I have to say though that a CO2 injected tank without pearling suggests a possible nutrient problem or your water agitation is removing the gas as quickly as you are adding it. Its unlikely to be low light since I would expect plants to bubble regardless when a surplus of CO2 is around, but I guess its possible. I would err on the side of those people telling you not to agitate the water. When I inject CO2 I try to not agitate the water either. With CO2 pumping into an aquarium I am less concerned about the gas exchanges I have been talking about since the CO2 will make your plants produce more O2 for your fish - as long as the lights are on. But I do err towards high light levels - not a fan of dim tanks at all. I recently tried a low light setup and it was a total disaster. I prefer to lower the light duration than the light intensity. 5 hours is my typical indoor schedule (100% artificial light) but outdoor tanks only get 2-3 hours of direct sunlight plus some indirect daylight the rest of the day.

To sum up a tank with CO2 injection and no pearling at all - sounds a bit suspicious to me. Something doesn't sound right. Dirt or no dirt. I would be tempted to add some liquid fertiliser to see what happens.


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## Hank Junior (Oct 1, 2020)

mistergreen said:


> Your natural waters might have naturally dissolved CO2 higher than what's available in the air. It might be fun to try to measure your CO2.
> Take a container of your water and microwave it till it boils away all of the CO2. Measure that pH on that and water in your tank.
> Use this formula to find the CO2 concentration.
> CO2(ppm) = 3 * 10^(pH2-pH1)


Ah yes you may have just clarified a mystery of mine which has been bugging me for almost a year now.

My source waters are:
1. PH8/GH10/KH7 (river water)
Strangely I have been to the river that supplies this and measure the water there - it was much harder - if I recall correctly the GH measurement off the scale - I stopped adding drops after about 15 drops as I wanted to conserve my test kit! It was surpisingly different to what I have supplied to my farm.
2. Rain Water - PH5/GH0/KH0
The GH and KH readings didn't surprise me but the PH did. As an amateur I was originally expecting rain water to be exactly PH7. Then I went online and found out that rain water is slightly acidic and usually PH6 if I recall because of dissolved gases? it varies it seems? I wasn't sure if I had measured incorrectly and wanted to believe the PH colour I saw was 5.5 but I think it really was closer to 5.0?
After all this talk about CO2 content and water it seems that the CO2 content may well explain the low PH.
Its water that runs off a roof and will always contain a bit of dead frog, insects and leaves (when you drink this every day it helps not to think about this unpleasant reality too much) - so I naturally thought that maybe the mud at the bottom of the rain tank (never seen it, but suspect it is there) is changing the PH a bit. 

The only reason I presently use 50% rain water and 50% river water in my 20L tank is I have tried both and not sure which is better yet so decided to use both and hedge my bets. Tank began 100% rain water, then became 100% river water and is now 50/50. Seemed do well either way except for the recent catastrophy but I suspect that the switch in water is not the cause of my problems. The reason I stopped using 100% river water was because my crypts that were once flourishing in this tank are now barely alive and are in the hospital (tank) - not sure when I will ever be able to take them out? They are in intensive care with CO2 injection maybe all that is keeping them going? The liquid fertiliser I use on all my other plants doesn't seem to help them at all. As my crypts got worse, my lilaeopsis got better? Very odd, can't understand it. Well at least my lilaeopsis and hair grass are thriving.


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## mistergreen (Mar 3, 2007)

Yes, rainwater collects lots of CO2 as each drop falls through the atmosphere. CO2 likes to dissolve into the water forming carbonic acid.
Crypts don't like abrupt change and will melt to adjust to the new environment. Whatever water they're in, keep it constant.


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## Hank Junior (Oct 1, 2020)

MrGreen after all my eulogising about the importance of gas exchange and keeping the water surface clean I am not so sure today. Did my weekly 50% water change (river and rain water mix) just now (this time not adding daily fertiliser) and the bubbles I have just seen are the equal of any CO2 injection I have ever had - unbelievable. Its 100% the same as CO2 injection. The plants remained completely submersed during the water change never, they never saw the air. By tommorrow the tank will return to normal again. I think my water sources must be extraordinary - someone did tell me recently they thought I had magic water - maybe I do? If I got these bubbles every day I would never need to even think about a CO2 cylinder.

Yes - my crimes against crypts are many. The reason for their recent abrupt chop and change is a desperate attempt to keep them alive. I still have the original plant I bought from the store but he is in a bad shape. His offspring are hanging on. Fortunately managed to get about 6 or 7 baby crypts to keep going. The cycle that's been going on for months now is a baby crypt or new leaf arrives looking perfectly normal and a healthy green but as it matures it becomes sick looking deformed and olive brown/yellow and generally does not grow very much. The brown I have seen before but the yellow is not a good sign. Strangely the phenomenon doesn't kill them just makes them look sick.

It is likely that all the chop and change has made the problem worse as you say - they don't like change.


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## mistergreen (Mar 3, 2007)

Yup, some people do have magic water. There’s a guy on YouTube with a fish room full of plants with no added co2. I think his channel is MD fish tank. All he does is provide a rich substrate and fertilizer.


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## jakobkiloa (May 23, 2021)

Daphnia eat green water algae so when you have a healthy population they keep the water cleaner but they do require some green water or they will die. Now I know in green water without gas exchange they will die as well. gimp 2.8 download


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