James/Ed,
I've thought about your points and while they do seem reasonable, they bring up more questions than they answer. Now, remember my arguments are based on premise that NH4 + light cause algae. If you don't buy that premise then the arguments are not valid.
James, I remember that urea experiment you did and Barr brought up the strong possibility that the filter and sediment bacteria were reducing the ammonia in the urea via enzymatic action of urease. That would mean the bacterial reaction to NH4 is very quick, and that suppression of NH4 spikes are attributed to rapid nitrification.
I guess I also disagree with the assessment that "...tiny amounts of ammonia..." are produced in a planted tank. I would argue that the ammonia production is high and is constant simply by virtue of metabolism. Just consider the amount of ammonia generated during a tank cycling. That ammonia production rate never stops, and in fact it accelerates when we add plants and animals and food. It's just that we measure a low concentration level because the NH4/NO2 is being processed. Barr brought up the point in that thread that if you thought ammonia production in a tank was low, all you need do is to turn off your filter for a while and see the results.
All we have to do is to look at our empirical evidence. How many reports are there of algal blooms in a planted tank? Algae has become almost a central theme. A contributing factor? Ammonia production not attenuated by the available bacterial colonies. So what you say is true, that low stable levels of ammonia keep the blooms at bay but how does one achieve low stable levels? Its certainly not stable when one feeds the fish for example. Metabolic rates and organic waste decay are not really all that stable as the plants grow or are trimmed, or when water is changed. I would argue that an aquarium is the least stable aquatic environment known to man. If sintered glass media or sponges function as we think they do, by making space available for hosting bacteria, then more space means that a rise in NH4 allows these germs to increase their population more easily. If less space is available would this not affect the rate of bacterial population increase necessary to consume an NH4 spike?
We observe that detritus and organic waste buildup stifle a filter by blocking the pores of the media reducing the bacterial population. Detritus sitting in the filter breaks down into ammonia which fails to be processed by the colony. The result is often BGA if filter maintenance is not performed. It seems obvious to me that if you have more filter capacity to begin with the likelihood of this condition is reduced. Maintenance is still required, obviously but you have more biomedia and space to begin with so the effect is lessened and your margin of error is widened.
I also don't buy the assumption that bacterial populations are necessarily limited by NH4 availability. Of course this could be the case under certain conditions but we really haven't measured populations versus NH4 concentration so this would be speculative. Also it's not certain that all the NH4 in a volume of water is removed during a single pass though the filter. So if I connect two filters in series this assumption would mean that bacteria colonies would be established in the first filter and not the second. Clearly, while the available space is not completely filled in both filters the available space represents a potential that affects the speed at which the population can increase. This population agility allows absorption of ammonia spikes which occur constantly.
Again, I refer to the urea thread in which Barr referenced a list of K.R. Reddy journals. Further investigation reveals that bacteria, like plants and animals require more than just Nitrogen to prosper. They require Carbon and Phosphorus as well as other ingredients. So a bacterial population could easily be limited by the availability of other nutrients. Like Nitrogen the other nutrients must be in the right form for them to digest. Some bacterial species can obtain their nutrients in a variety of forms (i.e. organic and/or inorganic) or they can use substitute elements for their biological processes, such as Sulfur in lieu of Oxygen. Other species are less agile and suffer die off if their specific needs aren't met.
We all agree that flow is definitely King, but I view the extra filtration capacity as a "shock absorber" that processes ammonia spikes which helps to suppress algal blooms. It is difficult to quantify though how much of one's success is due to the extra flow versus the extra filtration capacity. :?
Cheers,
Have you seen Barrs latest 180G effort? It looks fantastic until your eyes wonder over to the rocket propelled grenade launcher on the left, ugh...
Your not helping!! 
