Filter FLow Rate And Algae Growth ?

[Thanos Naranja]

My Wife set up our 33 gallon Hex tank about 1 year ago. She has had it running stable the whole time except for recurrent red and brown algae growth. She has a Millennium 2000 on top and an under gravel with powerhead. We have never had any green algae growth. Recently I took an interest in the tank because of her algae complaints. I decided she needed a more complete eco-system and purchased a large algae browsing snail, a Hermit to pick up left-overs, and a Chocolate chip to filter the surface and browse the edges. The snail made short work of the red algae, but still no Green algae.

Is it possible to pump water through the Millenium filter so fast that we make it difficult fo the good algae to get a foothold? Any suggestions?

[OrionGirl]

Actually, adding some powerheads (not plugged to the UGF) will help you increase water flow specifically where it's needed. What are the nitrates like? UGF are seldom used in SW, since they can run with sand, and prevent the areas of anaerobic bacteria from developing. I would remove the UGF, and the substrate, and put in 3-4 inches of sand, and have 30-45 pounds of live rock. A few more cleaners would likely help as well--more grazing snails, more hermits. Chocolates can be a problem--they will go after some other inverts and corals, but are fine in a FOWLR.

[Thanos Naranja]

Or UGF is topped with 10/15 LBS of shell debris not sand. Our research at Aquaria Central on the problems of mechano-chemical filters like the Millenium positively inidcated the need for a UGF in the marine environment. to get the right acerage. All nitrates, nitrites, phosphates and a salinity are in the normal band. Yes we have had short-lived episodes of imbalance that we were abvle to quickly correct. Is it possible to seed the green algae in?

[mogurnda]

It is certainly possible to keep a marine tank with an undergravel filter, and I have done it in the past. But it is very important to keep the gravel clean by frequently vacuuming it. Otherwise it will clog with debris and become a source of pollution. In the long term, I agree with OrionGirl that you might want to think about live rock and a deep sand bed. Believe it or not, it will reduce the work and increase the health of the tank.

But you were asking about algae. What kind of green algae are you interested in? Something that grows in sheets, or is more hairy? By and large, people try very hard to keep these to a minimum. Possibly a way of getting algae that you want into the system is to buy a piece or two of live rock that contain the species you want.

[Thanos Naranja]

So what you're saying is that the sand bed will provide a physical structure in which benficial bacteria can grow? We had a large bacterial layer under our filter prior to our major annual cleaning.

How do you clean sand, or do you even need to? I'll admit that a nice snow-white sand bed would be nice. But it would mean turning the current tank upside down. I suppose more research is needed and then maybe next year. I get the point about the live rock as an algae source, and I have looked into local sources. We currently have a large Finger coral fossil in the tank we picked up while on vacation in Fla. and a large Giant-Barnacle cluster from the Philipines that provide an excellent fish habitat. Maybe the green algae is not such an important thing. The inhabitants aren't suffering after all!