Saltcorner
By Bob Goemans
By Bob Goemans
Hello Bob,
I am a partner in a pet shop in Greeley Colorado. We focus on aquatics and reptiles. Six months ago I began my own personal reef tank at home. I studied thoroughly before taking on the microcosm. I read the Reef Aquarium books by Sprung and Delbeek, Natural Reef Aquarium by Tullock, and browsed many others over the years. I had heard of the amazing results of the plenum and found myself very interested in that system. There was not much information on the plenum, only how wonderfully it could work. I had also found some information about live sand bed filters. I had spoken to some employee's at GARF and they were fairly helpful but some miscommunications between us may have caused my personal tank some problems.
My tank is a 72 gallon bowfront. It has four 55W fan cooled compact lights. Two lamps are 10K and the other two are Actinic. I also have one 40W Blue Actinic T12 bulb toward the back of the tank.
I also have a 20 gallon sump/refugium with a high performance protein skimmer built into the return side of the sump. Some prefilter sponges follow the skimmer, and then an eggcrate plate about 18" x 18" with some live rock growing sawtooth-like Caulerpa algae on it. The sump has its own lighting system, two18 watt compacts that run nine hours at night opposite the lights in the show tank. I have read this may help to maintain pH levels at night. The Caulerpa grows great and coralline algae grows on the live rock and walls of the sump.
In the show tank I have plenty of alternating water flow rolling from the top back of the tank toward the front bottom. Not round and round but rolling top to bottom. I have Powersweep powerheads that continually alternate the flow of water in the aquarium. I do not notice any serious detritus build ups on my live rock. Many hermits and snails keep my 90 pounds of live rock clean. My live rock is suspended above the substrate on aragonite arches that I built from advice from GARF. I really like the arches. Everything is covered in coralline algae including the exposed parts of the arches. My corals with large polyps seem to do pretty well, my polyp colonies do well, feather dusters, Xenia, cnidarians, all do very well. On the other hand I have had problems with SPS or stony corals. Discoloration, some black bacteria, and red cyanobacteria have invaded my branched stony corals. Most have been lost.
Some stony corals are growing, but Acropora, etc. are not. My big concern after reading one of your new booklets is that my show tank has a 3" deep 'very' fine aragonite sandbed!. Yikes! I think the hermits are keeping cyanobacteria to a visual minimum on the sandbed but not on the branched corals. My phosphates are next to undetectable but my nitrates have begun to creep up over the past few months. I tried a red slime remover (a mix with Erythromycin) and it did eliminate the slime algae. But, discoloration of almost all of my stony corals has me concerned. The Acropora corals lose their pretty tips, turn white then black and die. I will not attempt any more corals until my problem is solved. My lamps are new, and kept fresh. Calcium levels between 390 - 420ppm, and iodide levels are normal. I think my sandbed may be a mistake. I am considering removing the sandbed and replacing it with a plenum in the tank.
I will move the inhabitants and live rock to some bins I have with the powerheads and aeration. I will keep most of the original water not disturbing the sand bed. I will scoop out the sand bed carefully. I will place my new plenum in the tank with 2 - 3 mm aragonite coral over the plenum. The aragonite will be 2" deep with a 2nd screen layer and 2nd aragonite layer 1-2" deep for the top layer.
* Should I add any of my old fine live sand to the top of my new layer of aragonite coral?
* Is this a solution to my problems?
* Is this going to be dangerous to the short term health of my existing corals?
* Would it be wiser to slowly remove sand until it were only 1" deep.
My original plan was an in tank plenum but I thought my small sump plenum would do the trick. Obviously it is not. I also found that GARF uses aragonite coral, not fine sand for all of their 3 - 4" live sand bed filters. That may have been my big miscommunication! I may be totally off base with my problem, if so let me know. Thank you so much for your time.
Sincerely,
Aaron Blake
Hi Aaron,
Thanks for your letter and that booklet has been out for almost two years. Unfortunately, you did not see it in time! Misinformation in this hobby is certainly a problem, however, where GARF is concerned, they are one of the better aquarium product companies and it sounds like a misinterpretation on your part.
As for your aquarium, start over! Do not use any of the old sand as it is far too fine for a plenum sandbed. In fact, its too fine 'period' unless you want to replicate a swamp! Follow the instructions in my booklet.
As for your sps corals, you don't mention alkalinity level, which is a prominent player in the carbonate buffering system. Also, sounds like the light may be insufficient. I would consider doubling what you now have. When the tips of Acropora lose their color, that's usually a sign of insufficient light intensity. And bacteria growths among the coral branches can be a sign of insufficient water flow in those areas.
As you now probably know I don't sell aquarium products, never have. My goal is informing the hobbyist through my writing and low cost booklets on what constitutes better aquarium husbandry. In fact, checkout my new non-profit website at www.saltcorner.com. Hope this helps, and keep me posted,
Bob
