Tall tanks

Question
QUESTION: I have a newly setup wet/dry saltwater aquarium. I moved inhabitants from a long tank to a tall tank, advantages, arcylic over glss, wet/dry over biowheel but all in all I have probably less light reaching the bottom and less surface area. I have since done my research, however I don't want to risk moving everyone again cause of the stress they are already under. Has anyone maintained reef and saltwater setups in tall tanks? Any advice. I have a sea anemone, a clown fish, several corals, lots of live rock, crushed coral and live sand, hermit crabs and snails, as well as two different species of starfish, one chocolate chip and the other one is a bottom feeder.

ANSWER: Hi Aaron. Tall tanks definitely have their disadvantages, especially in a reef set up. Even though you may have a large volume of water in a tall tank your stocking level capability will be far less then in a tank of the same size that is long. With that said you may have to upgrade your lighting to ensure it is reaching all the corals in your tank. Either that or try to make sure everything is up high in the tank. Of course you can successfully keep a reef tank in a tall tank it is just better to do so in a long tank.  If you just recently made this move you definitely don't want to stress anything out further by moving them back. Some corals will adjust over time to a little less light however if you are noticing a drastic reduction in polyp extension or any of your corals are paling in color you will need to get some stronger lighting over them. There are lots of wonderful choices for lighting out there and your tank can not possibly be deep enough that there isn't a light out there that can successfully illuminate the bottom of your tank. I was at a tradeshow last spring and one of the most beautiful tanks I have ever seen was in a tall tank. It was a custom made tank about three feet tall. At the bottom of the tank they had some beautiful sun corals and gorgonians where the lighting was dim. As you looked up the tank, they had placed all the corals up the tank according to the light level. On the top they had a beautiful pink acropora. It was truly amazing! They only had a single metal halide pendant lamp over this tank. So to answer your question yes I have personally seen a successful reef set up in a very tall tank. Placement was the key to its success and the lighting was the proper lighting for that tank.

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QUESTION: I have two 9 watt coralife bulbs, u-shaped, one white, one blue. Today I created a pile of rocks almost halway two the top and placed all my corals but one on top of thet. My tank is about three feet tall. Everyone seems happy except my chocolate chip starfish which has been on the bottom for days now, which is unusual for him. My ph is low and I think it may be due to the amount of carbon monoxide in the water, based on what I have read, especially with a tall tank. I added an air filter yo the top tonight. Any suggestions?

ANSWER: Hi there. You are absolutely right. If there is very low water movement in your tank then the carbon dioxide will accumulate and form carbonic acids which in turn will lower your pH. Simply increasing the current at the surface of the tank may not be enough. You may want to consider adding a small powerhead down towards the bottom of the tank so the water gets circulated better down there as well. You may want to check your alkalinity as well. If there is a build up of organic acids and phosphates they will tie up the bicarbonates and calcium carbonate and reduce the capacity of the buffer system of the seawater to maintain a higher pH. excess withdrawals from the buffer system by the accumulation of organic acids are only corrected by partial water changes or additions of bicarbonate or carbonate. To determine if the pH is low due to a build up of CO2 or due to the accumulation of organics simply test your pH then take a small amount of water out of your tank and place into another container. Place a powerhead or use an air pump to vigorously aerate the sample water if after about 30 mins you retest the water and the pH is higher then you will deffinately know it is due to the CO2 in your tank. If the pH of the water remains the same then the low pH is due to organic acids and more frequent partial water changes need to be performed.
I don't know what size tank you have but two 9 watt bulbs seems very low for a tank that is three feet tall. Are they compact florescent? Or are they vho lights? 18 watts total lighting seems a little on the low side and you may want to consider upgrading your lighting system soon.


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QUESTION: They are compact florescent. I can't fit anything much bigger under the hood. It's a coralife light, with two compact florescent bulbs, one blue and one white.

Answer
You may want to consider an open top system with a light fixture that rests on plastic stilts fastened to both sides of the tank. hoods are not good for the proper exchange of gases at the surface. The more air that can circulate on the surface of the water the more CO2 that can be released. Also with a tank being as deep as yours is, the rule of having 4-5 watts per gallon of lighting goes up to more like 5-6 watts per gallon to keep corals thriving. At 18 watts your tank would have to be around 5 gallons for you to have adequate lighting for your corals. Is it? Lighting will definitely become an issue for you corals and anemone. Even some of your more hardy corals will still require at least 3 watts per gallon. Unless you can move everything right up to a few inches from the top I am afraid your corals are going to suffer. Depending upon the length of the tank you can get some pretty strong lighting in a small area. There are allot of choices out there and it may just be something you may want to consider doing for the health of your corals. I have seen some pretty successful tall reef set ups but one thing they all had in common was strong lighting. This is one of the disadvantages of having a tall reef tank.