Saltcorner
By Bob Goemans
By Bob Goemans
Hello my friend,
You don't know me, but I tell my friends you are my mentor. I have read your columns since their conception in Marine Fish Monthly, which goes back over fifteen years, and now follow them in FAMA. And I thought you should have this feedback.
I have a 55 gallon plenum that has been on going for 5 (maybe 6) years now. It has been marvelous in performance. Algae is almost non existent, nitrates are, always have been, unmeasurable since it cycled. I also have a 75 gallon Berlin system that is 12 years old that is now coming down for replacement with a 180 gallon tank. This has been a reliable tank, but not like the plenum system!
Unfortunately, a few years ago I suffered some serious health problems, which as you can guess put a real load on my wife when it came to tank maintenance. The plenum system required very little maintenance, the Berlin, of course, a lot more. The plenum came through unscathed while the Berlin did not fare as well.
Now that I'm feeling better and am ready to move the Berlin system into the 180, I have a few questions. I want to use a remote plenum. You have written that you set up a 180 using a remote plenum. I have a 55 and a 75 gallon long that I can use for a remote plenum. Which one should I use? Do you have any diagrams, which show the best way to get water in and out of the remote plenum? Also I need to get water to the protein skimmer which I am considering using the sump for. In your new CD book you say to use 2 mm grain size sand. CaribSea has a product called 'reef sand special blend' which has some smaller grains like 1.5 to 2mm. Will this work ok? I will set the eggcrate grids on 1 inch PVC pipe and wrap them with fiberglass window screen. Any comments? What's your thoughts on using 1/2 live and 1/2 dead sand?
Thank you my friend for all the help you have given me and others over the years. Although we have never talked before, your guidance has always been there.
Grover Cannon
Eugene, OR
Hi Grover,
It does my heart good to see such honestly in one's mail, yet it saddened me greatly to hear about your health problems. I wish you the best future possible and I mean that from the bottom of my heart.
As for your questions, let me address first your question to place the plenum in an interconnected tank, i.e., auxiliary plenum system. This method has become widely accepted, as many aquarists simply do not like the look of a very deep bed in their main system. Not only has it resolved that issue, it is proving to be more easily maintained when not cluttered with live rock formations and various coral animals. My 180 gallon solar powered reef aquarium used a 60 gallon plenum tank under the main tank. However, that main tank had 27 fishes and was fed as many as six times a day. I found that size interconnected plenum system not capable of keeping nitrates below 5 ppm, as originally desired. Its nitrate stayed about 7 ppm. Therefore, it only seems reasonable to assume a slightly bigger plenum system would have reached that goal. Because of this personal experience, I now think the interconnected plenum system not be any smaller than half the size of the main tank, and therefore would recommend use of the 75 gallon tank.
I don't have a diagram showing how to do that, but can say the water from the main system should overflow a standpipe or overflow chamber and gravity feed into the lower plenum system. I used a SEN 350 located in the sump to return water to the main system. Where the water entered the main system I placed a control valve to regulate the amount of return flow. In fact, that control valve was the type found in RIO pump boxes and it worked well. Flow from your plenum system, if the 75 gallon tank is used, should be about half its volume, or about 40 gallons per hour, and that's the reason for the inline control valve. A somewhat more flow is also possible and feedback is showing that even higher flows work well. How high, still needs more input data, but would guess at this time your return flow could equal that of the remote tank.
When it comes to sand grain size, anything in the range of 1.0 mm and above to about 5 mm will work nicely. The 2.0 mm is an average size, and CaribSea does have sand that is somewhat larger than what you mention. Its their Seaflor Super Reef product, which I consider the best choice size wise. In fact, it now comes package 'live' and that helps shorten the initial cycling time. You could also simply use crushed coral, as that will also suffice size-wise.
And, as for half live and half dead sand, that's okay, but place the live sand on top. As for the plenum grid, it sounds like you have the right idea, but if any questions remain, ask before it gets cover with sand. Lets do it right the first time, but then your 55 has been doing great for five years, so it seems you understand the requirements.
Otherwise, appreciate your letter, enjoy and stay well.
Bob
