Saltcorner
By Bob Goemans
By Bob Goemans
Hi Bob:
First of all I would like to thank you for all the information you provide through your column, your booklets, and your new CD book. I have enjoyed them all.
In an attempt to lower the nitrate levels in my 90 gallon fish and anemone tank, about 50 ppm, I have decided to add a NNR plenum to my system. Presently I have about 70 pounds of rock, a small protein skimmer and trickle filter combination, a canister filter for my activated carbon, as well as a UV filter. I only have a few fishes and a couple of anemones, with all other system parameters okay. Yet, I want to lower that nitrate level for my own satisfaction and prepare for the possibility of expanding to a reef system at some time in the future.
I interconnected an old 50 gallon aquarium for my plenum and have followed you directions to the letter, with one exception. I used 1" strips of eggcrate on edge around the outside of the grid and a couple of cross supports. I tied these in place with plastic ties. This gave me a sturdy bottomless box that allowed me to glue the screen to the bottom edge of the 1" strips and have a very neat and tidy covered grid. I haven't used any live sand in the system.
My question is, can I just hook this into my existing system (after the water has cleared) and allow it to cycle within the system or should I cycle the plenum on its own before opening the connection between the two systems? Hopefully my water quality will improve, especially the nitrates, with the addition of the plenum. Furthermore, it has been extremely interesting doing the research and constructing the system thanks to your writing. Thank you again.
Dave Lineker
Comox, B.C. Canada
Hi Dave,
Thanks for your 'thanks.' As for using strips of eggcrate as support for the horizontal grid, I always tell people to position those strips so the square openings in the material are not vertical. In other words, place it so they allow for diffusion from the surrounding outer edge of sand or between sections under the grid. If that's the way you did, that's perfect.
As for your question, connect it to the main system immediately. The sooner the better. By using dead sand the bed will take about three months to become sufficiently active to show some results, somewhat less if one of the biological activator additives is used.
As for the efficiency of an interconnected plenum-equipped tank a doctor in Connecticut gave me some feedback about his a 500 gallon fish-only system. It also had 50 ppm nitrate. He connected a 30 gallon plenum system to his main system and water flowed through the plenum system at 15 gallons per hour. After a few months of operation the effluent from the plenum contained 25 mg/l nitrate. Great efficiency for such a small interconnected tank and it say's a lot about plenum capability!
Keep me posted,
Bob
