# Plant vs. Algae Low/High Tech Ecology Concepts



## Mxx (Jul 6, 2011)

Having just completed a read of Wastad's Ecology of the Planted Aquarium, I'm convinced I'd like to try a hybrid approach of the low-tech and high-tech planted tank with my next large aquarium, by trying to take certain aspects from each. And I appreciate this is perhaps far from an El Natural approach, but I do keep reading that many hobbyists trying this approach still suffer from issues with algae. With the ideas and knowledge I picked up in Diana's book I hope to potentially resolve those issues fully ahead of time with my own set-up. I nevertheless thought the members here would be the most experienced and qualified to offer advice on my hybrid approach, so I look forward to hearing your thoughts. 

I would plan to use medium lighting intensity, pressurized CO2 to ensure lush planting, a MTS underlay under black sand (silica free) topping, and decent bio-filtration in order to accommodate heavy fauna stocking levels. In balance with those, I would aim for an otherwise stable balanced ecology with relatively limited water changed and manual maintenance. However, the problems with high-tech seem to be that the rapid plant growth seems to deplete the nutrients from the soil and substrate faster than the fish and fish food can replenish it. And that allelopathy from competition between plants can eventually hinder their growth if there isn't sufficient water circulation through the substrate provided by some means such as substrate heating cables. 

As the principle challenge for most hobbyists seems to be struggle against algae, I'd like to ensure that I'd have a system which is optimal for eliminating it while ensuring that my plants thrive, of course. And the key to doing that seems to be in how the substrate is used, and the fact that the plants are rooted in it, while the algae obviously is not. 

If I was to run a network of perforated plastic piping at the bottom of the substrate, and slowly circulate water through it in a closed loop, then could I thus do in-line dosing of fertilizer and CO2 through the pipes, which would continually supply the plants and substrate with all the nutrients they need while keeping those nutrients out of the water? Therefore the plants would be able to get all the nutrients they need through their roots from the substrate, while algae would have little if any nutrients available in the water? And the extra circulation would help rinse any allelopathy compounds out of the substrate. Therefore I suppose the lighting would be the limiting factor, and which I could either dial up or down depending upon how bright I would want the tank to look and whether I feel like dealing with much trimming once I've already achieved the desired amount of growth. 

I believe there were 2 or 3 nutrients which plants prefer to take from the water instead of the substrate, which I need to check about, but those could still be dosed into the water column if necessary. 

I'd try to keep the tank water relatively clean and sterile through filtration, while meanwhile keeping the substrate more-or-less saturated with all necessary nutrients. And thus, I could use bio-filtration with denitrifying media such as seachem matrix and carbon to eliminate ammonia, nitrates, and other nutrients from the water, despite that I would be dosing those into the substrate. And it certainly seems potentially easier and less messy than trying to stick root tabs underneath a hundred different plants every few weeks. Of course there would be some leaking of nutrients from the substrate to the water, but if I can monitor it and add just enough so that the plants are not showing signs of deficiencies then that could be kept minimal and filtered out quickly before the algae could really benefit. (It may even turn out that dosing extra nutrients is not even required, if I'm feeding the fish enough). And by injecting the CO2 into the substrate you might need to use much less of it as it wouldn't be off-gassing into the air as quickly. 

So, ideal environment for both plants and fish, while hostile to algae, right? Should this work as planned, or would there be some other inherent problems in doing this? Would lots of CO2 in the substrate cause excessive anaerobic problems, and would I potentially need to either add pressurized oxygen to the circulated substrate water as well to compensate, or just add it directly to the tank instead despite that it would be available there to algae?


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## Michael (Jul 20, 2010)

I don't want to discourage experimentation, but why all the needless complication?

If you use CO2, your growth rates will be high, and the plants will rapidly absorb ammonia, probably before a biofilter can take it through the whole cycle to nitrates. If you use chemical filtration to take all of the nutrients out of the water, what will your biofilter live on?

As far as keeping oxygen levels high in the MTS substrate, there are four low-tech methods available:

1. The mineralization process improves longevity of the soil by completing much of the breakdown of organic matter before the soil goes in the tank, reducing the chance of anaerobic conditions.

2. You can improve the physical structure of the soil by adding a fired-clay product like Turface or Soil Master Select--this decreases compaction and subsequent anaerobic conditions. (It also adds CEC capacity, which helps with nutrient storage and release.)

3. Don't use a small particle cap, like sand. Use a porous cap with relatively large particles, like aquarium gravel or expanded shale. Small particles in the cap inhibit gas exchange between the soil and the water.

4. Use some deep, strong rooted species of plants (Amazon swords, cryptocoryne, nymphaea). These plants actively transport oxygen from the leaves to the roots, and substrate.

To refresh nutrients in the soil substrate, is it really simpler to dose, maintain, and clean a recriculating system on a daily or weekly basis? Or just put some fertilizer pellets in the soil every 6 months or so?

An alternate method of preventing algae is to create good water flow--10 times the volume of the tank per hour, moving in a smooth, non-turbulent current. Couple this with a large capacity biofilter to buffer the system and take care of any water quality problems.

I understand where you are coming from; I tend to over-think things too. In my first planted tank, I wanted really good water flow, so I built this complicated system of power head pushing water through a manifold under the substrate. It didn't work well. Finally, I just increased the flow through my filter and carefully placed the outflow and intake to create a nice circular flow. It worked much better, and was simpler and easier to maintain.

But if you decide to build this thing, I really want to know what happens!


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## Mxx (Jul 6, 2011)

Why would I do this? - To try and best combat any algae prior to the start!

And it's not really doing anything that others aren't doing already, just in a slightly different way by trying to dose directly into the substrate instead. It seems that many people that are doing either the high-tech or low-tech approach still have significant algae problems, some don't, but I didn't want to leave that up to chance!

The topic does however beg the question of what controls algae growth, whether it is allelopathy from plants that are growing constantly, or whether you can deter algae by limiting nutrients to it, or CO2, etc??

This also begs the question of whether common aquarium plants can actually absorb CO2 from the substrate through their roots, which I'm not sure about as I've heard differing opinions on this...

If the bio-filter nevertheless isn't accomplishing anything because the plants are using up all the nitrogen, then that's perfectly fine with me. I just wanted to keep nitrogen out of the water column as much as possible to starve the algae. And so the bio-filter could be mopping up any that leaks out of the substrate as well if I'm dosing nitrates into it, with the algae having to compete against the established bacteria in a large bio-filter for nutrients. 

1. I'd be mineralizing the soil first, perhaps through a dry start method

3. I'd (heard) that water circulation through gravel can actually get plugged with mulm, while certain sands such as pool filter sand allows decent enough water circulation while keeping mulm on top until it disappears. I'd perhaps look at using the ceramic coated sand, (forgot the name), in order to avoid excess silica and subsequently diatom blooms in the tank. 

5. For a dosing fertilizer I'd likely just mix up a large container of solution and then have a peristaltic pump injecting it on a daily basis, so that shouldn't really require any effort at all on even a weekly basis. (Admittedly I do like automation and don't mind spending a little to achieve that). I don't mind the idea of dosing with fertilizer pellets, but if I have a large tank with significant depth and height with fully dense planting and thick carpeting plants as I'd be looking to achieve, I'm not sure how effectively I could place and distribute fertilizer pellets in order to ensure they reach every plant sufficiently with sufficient uniformity. And many of them could be difficult to reach and get pellets under without causing great disturbance, so at some point that does become a PITA. 

I appreciate that good waterflow can help, but I heard it's effective only up to a point. 

Basically, what I'm suggesting is almost like growing plants hydroponically, in that many of the plants would likely run roots into the nutrient circulation system even. 

It may very well be that a mineralized soil underlay would be more than sufficient for a few years, and only then would I need to dose additional nutrients through the system of pipes I'm talking about, which might otherwise be lying dormant until necessary when the plants start to show signs of nutrient depletion.


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## mthom211 (Sep 3, 2010)

A plenum would be a lot easier than what your wanting to do. It's basically just an under gravel filter with mesh over the top to prevent it from filing with substrate. Ferts are dosed into the tube thing that you would normally atach a power head too. 

By getting your NO3 to 0 will not really hinder algae, it will hurt your plants more than algae. Algae can use tiny, tiny amounts of nutrients in the water collumn. Some algae is actually caused by low nitrate, I have GBA in one of my tanks because my nitrates were zero. The key is to have all your ferts in ballance. Try reading some of the stuff Tom Barr has written. He floods his tanks with nutrients and has litle to no algae, this is because the plants arn't limited in their uptake of nutrients.


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## aquabillpers (Apr 13, 2006)

My NPT's rarely have algae problems. Sometimes there is a little BGA soon after the tank is set up, but that is easily handled. I do have hair algae in a few tanks, but American flag fish control that.

The way to control algae is to have a lot of healthy plants, and to keep light and nutrients at a level to maintain that, and no higher.

It's really pretty simple, which is the nice thing about Diane's approach.

Bill


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