CMG

Here is what I am in the process of doing;

I have a 40g tank with Under Gravel Filter and I want to switch to a bio wheel HOB filter because my hatchet fish are dying off from not eating and I am sure it is because of the stupid bubbles that the UGF creates because I see them try to eat the bubbles all the time and cant distinguish between those and the flakes.

So my question is this;

Can I just put the HOB bio wheel filter on the tank and turn off the UGF right away. The HOB filter package says not to, it says wait about 4 weeks for the bio wheel to create its beneficial bacteria. But I was thinking about it and my tank is already cycled/established so there is already bacteria in the gravel from the UGF so why would turning off the UGF effect that? Wont the bacteria still thrive in the gravel while the bio wheel builds up the bacteria?

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40 gallon FW Tank with a UGF & HOB Bio Wheel. A few rocks and fake plants.
Fish: 1 Pleco, 2 German Blue Rams (my fav. so far) , 4 Flying Fox, 4 Marble Hatchet, 2 Koolie Loaches,4 Congo Tetra, 1 Red eye Tetra
Just bought a 55g with built in wet/dry to start a SW tank FOWLR

Andyoybna

There should be plenty of bacteria in the gravel, since UGFs don't actually house any bacteria like other filters, you should be able to just yank it out, and be fine. Also, UGFs tend to inhibit the growth of bacteria to an extent, as well as pulling down organic matter deep into the substrate causing extra nitrates, and it doesn't allow nitrate to be turned into nitrogen gas either.

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Heymybigfish

definitly switch...do you have live rock? i would assume so. eitherway, i think its ok to just swap em out in 1 day....especally if your tank is already well established and cycled.

CMG

No I dont have any live rock, I am refering to my fresh water tank not my salt water tank. I will defenetly turn off the UGF when I get home But I dont know if I am going to remove it just yet. Maybe I should just remove it tonight and do a good water change/cleaning.

I am kind of in a rut with my SW tank since I am moving to a new apt. in a few weeks and dont know if there will be room for it, so I might have to just keep LR in there with no sand or fish until I can find a place for it and cycle/start it up.

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40 gallon FW Tank with a UGF & HOB Bio Wheel. A few rocks and fake plants.
Fish: 1 Pleco, 2 German Blue Rams (my fav. so far) , 4 Flying Fox, 4 Marble Hatchet, 2 Koolie Loaches,4 Congo Tetra, 1 Red eye Tetra
Just bought a 55g with built in wet/dry to start a SW tank FOWLR

pappyy3

Hi.

Just another option for you that no-one has mentioned as yet. (I'm NOT a big fan of underground filters ... )

If it's just the bubbles that you're worried about, why not add a powerhead to you UGF??

This means that you keep your UGF and get a better filtration due to the uncreased waterflow the powerhead will provide.

Just a thought