shane,
NH4 is constantly being produced in a tank and this production never ceases. It is independent of aquasoil, although this could exacerbate the problem. Uneaten food, fish urine and feces as well as detritus from the bits and pieces of the plants all decay and produce ammonia, every minute of every day. In a running aquarium NH4 never "=0"...ever.
The job of the filter bacteria that live on the bio-media, the bacteria that live in the water, in the sediment and on the surface of the plants and on any other submerged surface is to consume NH4. When more NH4 is produce than can be consumed by the bacteria then algae have a chance to consume the remaining NH4 and proliferate.
Healthy plants do consume some NH4 as well but if your dosing is suspect or if your CO2 is sub-par then the plants become unhealthy and lose their ability to remove NH4, thus they actually contribute to the problem by leeching NH4 and nutrients into the water.
This is a fundamental principle of algal proliferation and is one that you need to understand if you want to minimize the problem. The levels of NH4 that can result in algal blooms cannot be measured by your ammonia test kit as these kits have only enough sensitivity to determine the level of ammonia that is toxic to fauna.
Algal blooms can be triggered with NH4 levels far below what can be measured by hobby grade test kits. The higher the light, the greater the susceptibility to triggering the blooms.
Now, this is not to say that algae will not feed on any available nutrients once they form. If nitrates and phosphates are in the water algae will then feed on whatever resources are available, but the presence of NO3/PO4 cannot by themselves
cause the algal blooms to occur. This is another crucially important principle. If you change your mindset to the following formula-> "Light+NH4=Algae" you'll be on the right path. If you follow this path then the next path will be "how do I eliminate NH4 as much as possible?" One way is to make your plants as healthy as possible. Another is to directly reduce NH4 concentration levels by water changes.
Your high stocking level means that there is a large ammonia production via urine/feces and other organic waste. Doing frequent water changes removes large quantities of NH4 and organic waste. However if you don't feed the plants properly by providing large, stable quantities of CO2 and by dosing the proper quantities of nutrients such as NO3 and PO4 then your plants fail and actually contribute to the problem of NH4 buildup.
There is absolutely no point in blaming any algae problems on nitrate or anything else. If you have BBA this is telling you to fix your CO2 (or the distribution of CO2.) If you have BGA this is telling you to add more nitrate. No test kits can solve this problem for you. Algae is never confused, but we are often confused by all the myths, legends and optical illusions.
Fix your CO2 by either increasing the injection rate and/or improving the flow patterns in the tank (via additional powerheads or filter upgrades) and dose the appropriate levels of NO3/PO4/Traces. See the EI sticky thread for further dosing instructions.
Physical removal of the BGA and BBA is important - no doubt about that at all, but once removed it will only recur if you continue the same pattern that caused them to appear in the first place.
If you want to maintain such high stocking levels then it might be advisable to significantly upgrade your filtration.
Cheers,
