Who Gives A Fish Forums

I've been doing some aquariums again recently, got a few tanks set up with under gravel filters, and some newer ones like the Tidal and Aquaclear series. Still using my old Marineland hang on tank canister filters too.

What's got me thinking is the long-term stability of substrates without water circulation. I get why people use sand for Cory's and earth-eaters, but when you're planting or using deep sand, I'm worried about bacterial growth. If you use shallow sand, those fish just end up stirring it up anyway.

I'm about to set up another tank and I want to use sand for my Cory's, but I'm thinking maybe just a thin layer on the glass bottom, and then use artificial plants, or even just use my houseplants and floaters. That way I wouldn't have to worry about the sand causing problems. If I want to add more live plants, I could just use some kind of pot or container.

I've got some industrial filter mat material that could work to hold the sand over the under gravel filter plate. I've heard of people's older tanks crashing and I don't want to lose my fish, so I'm trying to minimize maintenance and maximize stability.

Any thoughts or suggestions before I start the next setup?

I've had a good run with UG filters back in the day, but it's been 25 years since I last used one. No issues with substrates for me, ever - I've mixed and matched playground sand, pool filter sand, and small gravel without any problems. For plants that need a little extra, I just use root tabs and they thrive.

I've been thinking about this a lot, and I have to say, I'm not sure sand is the best choice for under gravel filtration. I mean, it's just going to sift down through the filter plates, and that's not good for the tank. Even with that industrial filter mat you mentioned, bettaMagenta, it's only a temporary fix - it'll get clogged up eventually and you'll have to tear the whole tank down to clean or replace it. But, I do think you can make under gravel filtration work with fish like corys. You just need to use the right kind of gravel. I'd recommend using the smallest size that won't fit through the filter plates. Something like small, smooth gravel that's been processed to remove any edges should be perfect for bottom dwellers.