[StirCrazy]

you still want to shoot for a 5X to 10X / hour changeover rate in a fresh water tank, the things you will want to vary acording to the type of fish is the force of the water flow. this can be done by having several larger pipes comming offf your return for s slow gental flow instead of one that will act like a nozzle. I have a 10X turnover in mine but about 1/2 the tank has a very low flow as I have some fish that like that.

do you have a lot of plants in your tank? If so that stuff in the gravel is good for them, I use MTS (Malaysian Trumpet snails) to help controle this along with Kalua Loaches. The MTS stay under the gravle all day and at night come out and clean everything.

IMHO undergravel filters should be taken out and throwen in the garbage, they work good for about a year and then you have to rip the tank down to clean them of deal with problems from hell when the get gunked up. I have redone several tanks now as I used to use UGF and each tank as soon as I removed the UGF and put a power filter or a canister filter on it all the problems went away. another big problem for UGF's is if you have plants. The roots tend to get into them and plug them up rendering them useless way faster than they do it on there own.

Instead of a UGF I would recomend to anyone starting up a fresh water tank to go with 4" of a 1 to 2mm sized gravel and if your fish will alow it.. a few bunches of some fast growing stem plants like Hygrofillia (not sure of the spelling) my tank is at the point that I have c go away for 4 or 5 months and if all the wife does is feed the fish all my levels will still be perfect when I get home, (ie. 0 nitrate, 0 nitrite, 0 amonia ) although normal I do a 1/3 of a tank waterchange every month. Ieven had my kid dump a whole jar of food in the tank and the plants and snails took care of everything .. I didn't even get a reading out of it.

I have been toying with the idea of adding a sump to my tank, (or making my new SW tank into a planted tank). I have seen several taks with sumps and refuges in the fresh water side of the hobby, mostly people use sumps to hide equipment, increase water volume for stability, and to have a place to add water easy.. sounds familier eh [img]smile.gif[/img] as for the refuges mostly I have seen them in tanks whare people want to keep a critter that is benificial but will eat the fish and/or the plants in the main tank, or as a protected grow out area for food.

hope this helps a bit..

Steve