I've never actually seen what one looks like. I don't know where to find them. I don't know how they work, and I have no idea why people buy them. Maybe you guys can help me out here by explaining how they work and what benefits they have? I'm assuming keeping them clean will be more work since they are in the bottom of the tank....

Any info will be appreciated

They're not recommended for goldfish because of the waste they produce, but can work perfectly well with other fish.

You have a grid that is lifted above the bottom of the tank and is covered with gravel. A tube sticks out of the grideand an airstone is placed at the bottom of the tube. As air rises from the airstone, water is forced to circulate through the gravel, through the bottom of the tank, and out again. This increases cycle-bacterial growth.

Hope that clarifies it.

Crystal clear thanks Nenn
I was toying with the idea because I love wasting money that I don't yet have
I'm forever looking for things to buy for my little guys for 2 main reasons. 1:I love to spend money. 2:I love to spend money on the people I love. I love my fish, and treat them like they are my own flesh and blood

I hear ya!! Seems like everyday I see or hear about something and I'm like "Hm... I bet my fish would love that..."

It's hard not to spend money on them. They're so cute and totally dependent on you. I feel like it's my duty to do my absolute best for them, and who says I can't have a little fun while I'm doing it? Spend spend spend!

If I was rich, I would convert a whole room in my big mansion to a huge tank. Waterproof room with glass walls and a space at the top so that I can dive in and carry out the maintenance! What a dream....

=P Sounds like you should be a feeder diver at SeaWorld!

That'd be pretty cool. I might get eaten though...

Well, I guess there's always a chance you'll lose a few fingers, but who needs those?

Actually undergravel filters aren't unuseable with goldies! I thought that too! When I got my big tank it came with an undergravel filter & I threw it away. Now I wish I had it! I would not use one alone for goldies but it CAN actually help keep the tank quite clean & clear. There is a report that a very knowledgable person I know wrote on UG filters....hhummm, wonder if I can find it! You just have to understand how to maintain them properly!

Isn't there some type of "reverse" ug that keeps waste from going onto the bottom of the grid?

Maybe I have it mixed up with something else...

There is another way, to do them, yep the reverse flow of the under ground filter, but personally to me its just a waste of time and money with goldfish, they are just to messy and require alot of water changes and good filtration....


my 45 gal tank has

450 gph canister
450 penguin filter
350 penguin filter

I change 50% of the water every week, feed them 2 times a day and they are big babies, Pharoh is 7 years old and is 8 1/2" long now, just do to care and good water quality

I'm sure I wouldn't miss a few. I've got 8 to play with



Well if they're extra work I wouldn't bother anyway. I'm looking for something to make my life a little bit easier. I say 'life'....I haven't had one since I got the fish! What sort of fish are best suited to the undergravel filters then? I suppose they go best in the larger tanks too



I wish I could change 50% once a week...I'm doing that twice a day for both tanks! It's true what people say, you never have a life when you've got water to change.

7 Years old? I hope my fish live to be that old. I'm doing everything I can to sort the ammonia out but it's taking ages and I don't know how much more they can take

By the way Koko..Nice job on the Xmas theme

Is your ammonia in your tab water hun?

If not then you just need to change a bit of water every other day to keep it down, I would also add some aquarium salt 1 table spoon per 10 gals for now, this will help with the nitrites which will come soon, Also see if you can get stuff like Biospare or Cycle to help cycle the tank faster

Thanks about the xmas skin

Did you mean 'tap' water? lol. No, both the hot and cold taps in my bathroom where I get my water are free from ammonia. I test them once a week just to make sure. I'm dosing the tanks with roughly 1 tablespoon per 10 gallons at the moment and it seems to be doing the job with the nitrites. From both tanks I get readings of no more that 0.5ppm these days and the nitrates are about 25ppm. I just keep getting high ammonia readings from my ammonia dropper kit. Are the test strips more accurate?
I just ran out of Cycle a few days ago and I've run out of money for now

Thanks for the reply Koko