By Bob Goemans
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Bob Goemans corresponds with Ramon Vazquez (Puerto Rico)

Ramon Vazquez (Puerto Rico) writes...

Saludos; Mr. Bob:

I have been running a reef tank one year. It's 125 gallons and my equipment list is as follows; Tunze Comline protein skimmer, Calcium Reactor (Korallin brand), Wave 2K Wavemaker (corner unit), and sump 30” x 12” x 16” with a drip plate and a few bio balls. My top-up water comes from a SpectraPure RO and Ultimate DI unit, which is connected to the sump with an auto level controller. The return water is pumped by a MAK4 pump with a Sea Swirl device. There is also a Corallife Turbo twist UV, and a ¼ hp. Chiller (very old but working fine). The water from the aquarium goes to the sump by a continuous overflow device.

For lighting I have eight 96W PC lamps (4 daylight, 4 true actinic) with some blue LED moonlights. Lights go on at 8:00 AM (actinic first), then PC's at 10:00 AM. At 7:00 PM the PC's go out and then finally, at 8:00 PM, the actinics.

Actually, my tank is lightly stocked with few hard corals (Frogspawn, Flower Pot, Acropora, Yellow Cup, and a kind of green Acropora I like very much.) There are also some softies; a Chilli-pepper, couple of finger leathers, green mushrooms, small colony of Yellow Polyps, nice rock full of different color zoanthids, and two Toadstool leathers. Up to now have observed better growth on the hard corals than on the soft ones. The only thing I don't like is that the Toadstool corals sometimes stay closed for days and their growth is not as good as on the hard corals.

I have one blue tang, one yellow tang, a Puertorican damselfish, and a kind of very ugly blenny that feeds on algae films on side panels. There are inverts like a red banded shrimp, two turbo snails, seven nerite snails and two starfish that keep the thin sand bed stirred.

Would like to install a plenum out of the tank. After reading some articles and the book from Sprung and Delbeek, 'The Reef Aquarium Vol. 3,' am convince that to install a plenum is a must try. I am feeding my corals once a week with a product call “Coral Frenzy” and also adding once a week Reef Booster from Prodibio. Water changes are made very sparsely. The parameters of the water are not bad and my corals are looking good.

It will be very useful for me to know how small a plenum can be used for my set up. (I may sell the actual sump and adapt a small aquarium under the cabinet) Any diagram on the making up the plenum will be nice to have. Thanks in advance for your help.

Kind regards,

Ramon Vazquez

Puerto Rico

Bob replies...

Hi Ramon,

Thanks for your email, and from what I read, your equipment choices are very good, as is your explanation of the existing system. Nevertheless, I would have liked the system's water parameters, e.g., calcium, alkalinity, nitrate, pH, phosphate, and temperature as those might have helped define the problem with some of your soft corals. But will mention, if your leather corals are disturbed by any animals in the aquarium, they will close. Another possibility, - if they are subjected to low water flows, this can lead to them becoming coated with detritus/bacteria/microalgae and they will then close/shrink to rid their surface areas of this annoying/light blocking material. If these situations exist, it needs to be corrected, as they can remain closed longer each time disturbed or having to rid their surface of this material.

As to your question about the installation of a plenum in an interconnected tank, I would consider a 30-gallon the minimum, with a 60-gallon an ideal choice.

Visit my website at and go to the 'Photo Gallery.' Then open my 180-gallon system where one photo will show its 60-gallon plenum system under that tank. To its right were my calcium reactor, canister filter, and my water makeup tank. Worked perfectly for me. There are also some good articles about plenums and sandbeds in the 'Guest Articles' section you might want to read. Then open 'Bob's Books' and note the 'Live Sand Secrets' booklet, which 'totally' explains plenum systems and how to construct them. From there, if any questions remain, contact me and I'll be happy to help. For a custom-made plenum grid, contact Todd Schwarz at and discuss your need.

Hope this helps,




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