Saltcorner
By Bob Goemans
By Bob Goemans
Dear Bob:
I have read your articles about the remote plenum set-up you have used in your 180 gallon reef in your office. You said your old 125 gallon reef with a plenum was so efficient the nitrates were always zero, and you wanted to have a new system that would keep nitrates just slightly above the zero mark for the benefit of some soft corals and mushrooms. I was wondering if you set the plenum up with a slightly 'shallower' depth of sand, say 3 - 3.5 inches, would that accomplish the same goal of a "less efficient" system? I have written you several times before, and my plan keeps changing. I have a large tank that was given to me several years ago and have always planned on making it a fish-only tank, but have now decided to make it my new reef. It is about 225 gallons (84 long x 28 high x 23 deep).
Since it is so tall, I thought it would be a fine thing to have the plenum/NNR set up, which would bring the water depth to about 23 inches. I could still set it up with a remote plenum, but was interested in your opinion. I feel like the remote plenum system would be great, but then I would have to find a tank, or get one made to fit under my stand, which would take up most of the space and more of my budget. I plan to add a calcium reactor as soon as I can. My main goal for my new tank is to keep SPS corals (after a proper break-in period), so it may be better to have the plenum at full depth to keep zero nitrates. I am also very interested in clams and leather corals, which would all appreciate a higher nitrate level. I really value your opinion.
Thanks again,
Sonny Stokes
Hi Sonny,
A shallower bed 'may' accomplish a somewhat more nutrient rich end result, however, that would depend upon the overall bioload of the system. And yes, your high tank with a plenum would provide a more workable depth for maintaining the lower reaches of the tank. Just keep in mind the need to keep the sandbed surface as open as possible, as it is the 'gateway' to the valuable microbial processes in its lower depths. The more live rock, the more it becomes difficult to keep the sandbed surface clean and of course, to monitor for possible sand binding. Having a mostly unimpeded sandbed surface and of course, proper size sand grains for diffusion, is the key to plenum efficiency.
Keeping nitrates low as mentioned in my previous articles is important, however, so is the phosphate level. Good sps growth can be expected when alkalinity is in the 3.5 to 4.0 meq/l range, calcium is between 380 to 430 ppm and phosphate level is below 0.05 ppm, preferably under 0.015 ppm. So, when it comes to good sps growth the combination of a plenum system, calcium reactor and an excellent phosphate remover are principal players, besides quality lighting and water movement. Sounds like you are getting your game plan focused.
Enjoy,
Bob
