# Plant Meltdown in New Tank



## dwalstad (Apr 14, 2006)

Here's a private message with an interesting question that I got recently.

Question from DP: I just read your book a few months ago and converted my aquarium into one with dirt. It is a 20 gallon long with some medium lighting. It is in front of a window and gets some hours of indirect light during the afternoon. 
I did one inch of some cheap potting soil and 1/2 inch of pool filter sand. I planted in some dwarf hair grass and left it there for a while with the dry start method. It was only like three bunches of it. I also had some other plants that completely melted but that was my fault for not knowing they couldn't grow emergent. I just left them in the aquarium to decompose thinking it would add nutrients or something.

About a month and a half later I bought some contortionist Vallisneria, Ludwigia repens and Rotala. They were only a few stems, so the aquarium was definitely underplanted. Then I filled the aquarium the whole way and since no soil was disturbed I didn't need to do water changes. When I checked the ammonia and nitrate a week after soaking they were at 0 and the ph was at a 7.6. But now my plants are melting! When I poke the soil these big smelly bubbles come out so I think the soil went anoxic.

So my question is: Should I redo the substrate? Should I get some new soil and just do it all over again, and this time, plant it heavily? Or should I leave the substrate in and just add more plants?

My Answer: Sorry to hear about the plants melting, especially with all the effort you're putting into this tank!

The soil has gone anoxic, which you have already guessed. The stinky smell is H2S, which means substrate is _severely_ anaerobic. That H2S will kill plant roots in a heartbeat, meaning more decomposition and a worsening problem -- tank meltdown.

There's too much decomposition going on from the dying plants and the organic soil. And whenever there's decomposition, there's oxygen consumption.

I don't think you need to redo the substrate. You just need to get some oxygen into the soil and water. Poking the substrate with a pencil helps, _provided_ there's oxygen in the water, but I'll bet there's very little oxygen in your tank water right now. (I hope there are no fish in this tank.  )

I would introduce oxygen into the water and soil in some manner -- use a filter or a gentle airstone or even some vigorous "whisking" with a kitchen whisk several times a day. Then poke soil with a pencil. I would remove all dead plant matter until this tank starts to improve and plants start growing.

This oxygen imbalance is temporary, reflecting the typical 'Chaos in the Substrate.' The bacteria are just going nuts with all that organic matter -- and the oxygen is being sucked out of the substrate and water.

Once the soil settles down and the plants start growing (and producing enough photosynthetic oxygen to protect their roots), this problem will decrease. More oxygen will also solve the H2S problem.

Hope this helps!


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## Diana Prado (Mar 26, 2014)

Thank you very much! This is very useful. I didn't know how to tackle the problem, so your advice helps a lot! I will add an air stone and continue to poke the soil when I can. 
There are no fish in the tank but yesterday I found two baby snails! It was a great surprise and they are eating the algae that has started to build up. I was planning to slowly add more plants as my budget permitted. But do you think I should fully stock the tank as quickly as possible so that the plants can aerate the soil and fight the algae? 

Thank you again for your response! I loved reading your book and am very grateful to be able to reach you like this.


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## atc84 (May 18, 2013)

I thought this picture would add to the topic. This is a section of sand that receives the most flow from my filter. My sand likes to turn blue when it lacks oxygen, but under the filter it isn't dark like the area to the right.


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## Diana Prado (Mar 26, 2014)

That is very interesting about the blue sand! I'll try to keep an eye on how my sand is looking. There is definitley a dark spot in the back where one of my plants melted so I think that prooves what you are saying. 

Diana Prado


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## dwalstad (Apr 14, 2006)

Diana Prado said:


> Thank you very much! This is very useful. I didn't know how to tackle the problem, so your advice helps a lot! I will add an air stone and continue to poke the soil when I can.
> There are no fish in the tank but yesterday I found two baby snails! It was a great surprise and they are eating the algae that has started to build up. I was planning to slowly add more plants as my budget permitted. But do you think I should fully stock the tank as quickly as possible so that the plants can aerate the soil and fight the algae?
> 
> Thank you again for your response! I loved reading your book and am very grateful to be able to reach you like this.


It is always nice to try to help someone who is so grateful. Thanks.

Hopefully, some of the plants that you originally put in will start to recover with your new strategy. Because of all the trouble you've had, I would look for a sign of recovery -- a new leaf here, a new leaf there -- before plunging in again. It sounds like your tank will be fine, but I would hate for you to take a chance prematurely and not succeed. If you get plants, try to include some floating plants.

A picture of what's going on is always a big help. Glad to hear about the snails!


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## klinckman (Dec 6, 2013)

i never thought of melting roots with an anaerobic substrate environment.


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## arul (Mar 11, 2014)

Thanks for the input, Diana. My newly planted tank seems to have a similar problem right now. I have a 1" Lowes top soil substrate and Petco black sand 0.5" to 1" as the cap.

All my plants are melting. All the water wisteria plants died. The moneywort and ludwidigia repens have lost their leaves and the java ferns have got blackened leaves.

I should try poking the substrate with a skewer.

I removed my airstone the other day and added a new Koralia Nano 240 circulation pump, but it looks a little too strong, so I'm thinking of removing it and putting in a DIY sponge filter.

Do you think adding a DIY CO2 would be counter-productive? I would assume if the substrate is anaerobic and lacks oxygen, adding CO2 would be taking things to a worse level, but then CO2 is needed by the plants.


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## dwalstad (Apr 14, 2006)

arul said:


> Thanks for the input, Diana. My newly planted tank seems to have a similar problem right now. I have a 1" Lowes top soil substrate and Petco black sand 0.5" to 1" as the cap.
> 
> All my plants are melting. All the water wisteria plants died. The moneywort and ludwidigia repens have lost their leaves and the java ferns have got blackened leaves.
> 
> ...


Your letter brings up a most important point. There's a 1:1 ratio for oxygen and carbon dioxide. For every oxygen molecule removed, there's a CO2 produced. Any tank with low oxygen is going to have more than enough CO2 for plants. Therefore, in new tank setups with low oxygen, _please_ don't worry about CO2 for plants. Later on, when decomposition slows down and oxygen becomes plentiful, then you can worry about CO2.

Right now, oxygen is the problem, not CO2.


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## arul (Mar 11, 2014)

dwalstad said:


> Your letter brings up a most important point. There's a 1:1 ratio for oxygen and carbon dioxide. For every oxygen molecule removed, there's a CO2 produced. Any tank with low oxygen is going to have more than enough CO2 for plants. Therefore, in new tank setups with low oxygen, _please_ don't worry about CO2 for plants. Later on, when decomposition slows down and oxygen becomes plentiful, then you can worry about CO2.
> 
> Right now, oxygen is the problem, not CO2.


Thanks for the reply, Diana! I really appreciate it. I'll add an airstone on either side of the tank to get the O2 level up.


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## atc84 (May 18, 2013)

Isn't surface disruption the key to increasing gas exchange i.e. oxygen?


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## klinckman (Dec 6, 2013)

I always that Oxygen and CO2 levels were mutally exclusive from each other. 
Both can be low (low agitation non CO2 injected tank), 
both can be high (CO2 injected tank and pearling), 
high O2 and low CO2 (high light tank, that just used up most of the CO2), 
low O2 and high CO2 (morning before lights go on in CO2 injected tank)


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## dwalstad (Apr 14, 2006)

klinckman said:


> I always thought Oxygen and CO2 levels were mutally exclusive from each other.
> Both can be low (low agitation non CO2 injected tank),
> both can be high (CO2 injected tank and pearling),
> high O2 and low CO2 (high light tank, that just used up most of the CO2),
> low O2 and high CO2 (morning before lights go on in CO2 injected tank)


All the scenarios you have listed are true. However, in this plant meltdown situation, decomposition trumps everything else. That's because there is a huge reservoir of organic matter. Bacteria use oxygen to metabolize organic matter just as we humans use oxygen to metabolize food. The end product of that metabolism is mainly energy and CO2. Just as we expel CO2, the bacteria will expel CO2 into the tank water. The more decomposition, the more O2 consumption and the more CO2 production.

Thus, if you add a little extra oxygen to the system via good plant growth or water circulation, you can stimulate decomposition and CO2 production. However, if you circulate water and bubble air too much, you remove all CO2 and the plants suffer. The trick is to oxygenate water enough to keep decomposition going but not so much that you degas off all the CO2.

I think that you can use fish to gauge how much water agitation and bubbling you need. If the fish are doing okay in the early morning hours when oxygen levels are the lowest, the aquarium has enough oxygen for fish and decomposition. This is your baseline. Anything more is just adding unneeded oxygen and removing CO2.

Yes, it's tricky.


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## busymomv (May 25, 2014)

Hi all! Great and informative thread here. I'm in the beginning stages of a dirted / Walstad style tank and trying to figure out the balance of it all.

Tank specs:
1" MGOCPM w 1" gravel cap
36g 
8.5 hrs light from USA Current Satellite + LED (Split schedule 4.5 hrs on; 5 hrs off; 4 hrs on)
Mix of rooted, stem, and floating plants
3 or 4 small MTS (I think) and 1 large nerite snail
3 platys
1 betta

Its just about the end of week 3 and plants have grown for sure, nitrogen cycle is just about complete. (NH4/NH4=0; NO2=0.1; NO3=5) However, I noticed the plants weren't doing as well as I'd hoped at the beginning of this week - many of them had leaves that seemed to be decomposing, or holes in them, and some that were doing great initially seemed to be going "bad"; or the new growth slowed significantly. AND I noticed a few bubbles coming up from the substrate. 

So all week I've been poking the substrate 1 or 2 times a day, releasing bubbles I assume are H2S, and the plants seem to be much happier. From what I've read on this thread, and in Diana's book, I think that eventually the roots of the rooted plants will become established and the anaerobic soil will be less of a hazard to the plants and fish. How long should I expect that to take? If the H2S is being released by poking the substrate, and goes straight up via bubbles, is the water very contaminated? I'm happy to do water changes to be safe, but I'm not sure how toxic this situation actually is. Fish still seem well, behaving normally and have good appetites. Plants look much healthier and the decomposing has not continued since I started releasing the bubbles from the substrate / bringing O2 to the substrate/roots via poking it every day. 

Should I be doing anything else? or am I doing anything wrong that I should stop?

As always, thanks for your help!


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## SBS (Feb 26, 2013)

Increase surface agitation for increased oxygen levels in the tank, at least at night time. Make sure some flow is reaching the substrate too if possible.
Poking the soil is a momentary solution and won't "oxygenate" the soil much as it compacts back the moment you pull out the "stick" you are using.
The soil you've used is very rich and will need time and lots of oxygen to get mineralized. It can become dangerous to your fish if it pulls too much oxygen out of the water all of a sudden. Plus you need aerobic decomposition for CO2, not anaerobic, so the less anaerobic conditions you are promoting, the better. Nitrification also competes for oxygen at the same time so you need to promote the health of these types of bacs plus your fish, plus your plants at night time.
As far as I know hydrogen sulphide levels are dangerous to fish only if you can smell it as the levels human can smell are the dangerous ones. Plus it also reacts once in the water column so it isn't a huge problem to release it.

A planted tank is a learning process so at the start it's normal to go through a few bumps. Just be patient and eventually it should go well. Plants also can go through an adjusting period and when settled they tend to really start growing quickly but it takes time.
With the correct plants used, roots will grow around the substrate preventing the soil from compacting much and releasing oxygen, plus the soil will eventually "settle" once the bigger amounts of organics have decomposed.

I haven't had any such issues with mineralized soil.


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## busymomv (May 25, 2014)

Thank you for your response SBS - the hob filter I have creates lots of agitation and I can see the flow moving at the substrate level too, so I think that piece is under control. I was concerned that too much CO2 was being released since I cannot turn down the flow, but sounds like I shouldn't be concerned about that at this point and keeping O2 levels up is the way to go. The bubbles released from the substrate do not seem to have a smell at this point. 

If I ever do this again I will mineralize! Just didn't have the info about it when I started. For now, I will hang tight, be patient and poke away until the roots seem to take care of the substrate. 

I am so grateful for your guidance, and all the great info on this forum!! I seem to have avoided a melt down (for now)- thank you!


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