I just happen to come across a reef article you wrote in one of those free reef pamphlets by Instant Ocean. It's about the three types of bacteria in a DSB and how one may convert nitrate back to ammonium. I loved it because I've been telling people this for years this sort of thing can happen. I didn't know exactly how until I read your article, but have been saying that DSB technology is flawed, especially in deeper beds. Most people with these systems need to change enormous amounts of water to control nitrates. I can't understand this because DSB's were said to be so efficient.
In my still running Reverse UG filter, which I run very slowly with a filter in line with the incoming water, my nitrates are 5 mg/l. In fact, I just had my water checked by a professional water testing company in Canada and they confirmed it. I only change 20% of the water four or five times a year and in my 40 year old 100 gallon tank (just as you saw it when you were speaking in Brooklyn) I have over 25 fish. Many of them are spawning, so I overfeed the tank. Therefore this tank with should have very high nitrates, but all the parameters are perfect.
Thanks for contacting me, and it's been a long time since I saw your aquarium down in the basement and am very happy to hear it's still very successful. I still remember looking for the Brotula in the back of the aquarium!
As for that article, Marineland/Aquarium Systems asked me to write the introductory article for that return issue of SeaScope in 2007, which I though was quite an honor. In fact, that free publication had really been missed in the trade for several years. And since there was still a gap in the understanding of what really happens in the depths of sandbeds, especially plenum sandbeds, this was an ideal way to bring it forth to many that may not have read my writings pertaining to these aspects over the past decade.
The article made it quite clear that DSB's do reduce nitrates, unfortunately, they are sometimes reducing it to a better alga nutrient, and that is 'ammonium,' not ammonia, which is not useable by algae. In the process of reducing nitrate, it first reduces nitrate to nitrite, then ammonium, which is 'exactly' and let me repeat that, exactly what algae utilizes for food! As for phosphate, that's the compound used for 'energy' and between the both of them, copious amounts of algae can be produced in aquariums that are subjected to those processes! Ever overfeed and then see a green haze on the aquarium side panels for a day or two? Well, that's the microalgae that quickly fed on the ammonium produced by the wasted food!
I've found it somewhat disheartening over the last ten years as the differences between DSB and those in plenums has been thoroughly studied, yet some people still don't understand their differences or will admit that past anti-plenum writings were misguided. Nevertheless, bad press by those who wanted to have something to say that seemed logical, but was actually caused by their own poor aquarium husbandry, caused much conjecture about the plenum process. The sad part about it is that many have been frightened away from an excellent and very natural way to eliminate nitrate - naturally (Natural Nitrate Reduction (NNR)), the title of my original article concerning this method. In fact, your present overall results are an indicator that your UGF is acting somewhat like a plenum grid.
Hope things in your life are going well, and enjoy.