Fish tank technology

After keeping fish (mumble) decades ago I’m getting a small, 5-gallon tank to keep a betta in. The 15-gallon tank ages ago had a 3/8-inch high perforated platform that kept the gravel off of the bottom, the idea being that the water is drawn through the gravel colonized by beneficial bacteria to break down waste.

The new, smaller, tank has the gravel directly on the bottom and the treatment is handled by a box up high. It has a handful of porous ceramic donuts for the bacteria to grow in and a charcoal filter, about four square inches that needs to be replaced every three or four weeks. The tank is described as “quiet” – apparently more aggressively moving water stresses the fish.

Are these changes made in the past generation or so, or perhaps it’s the difference between bettas and other tropical fish – I did not keep bettas before.

I think you can still get undergravel filters, but probably not that small.

HOB filters (Hang On Back) have gotten much better and quieter over the years, and for one small fish should do a good job. The porous chunks for the good beasties to grow in are excellent, and in mine I swapped out the charcoal for a square of foam mesh for more growing surface plus greater trapping of debris. When I clean the tank I just rinse it in non-chlorinated water. I have well water so I can just use the sink, previously I’d siphon off a bucket full of tank water to rinse the media in.

I also have goldfish which are essentially beautiful, filthy beasts :stuck_out_tongue:

Bettas do like minimal current, so if you have a filter that you can control the flow that’s great. A sponge filter is a great choice too.

What saje said.

You had an under gravel filter. I never used those, as they are no good for planted tanks - my preference. HOB is the easiest/cheapest - especially for a small tank like a 5g. I used to use canister filters, but they are unnecessary for such a small tank. You don’t need to replace the charcoal that frequently.

And no - none of what you describe is “new.”

Bettas are pretty tough fish. The tolerate some pretty lousy water quality in the wild.

The HOB-style filter has been around since I started in the hobby in the early 90’s, but I can’t for for sure just when they came on the market. I’m no longer in the hobby so I can’t say how easy it is to find a commercial under-gravel filter, but they are easy to make for any size tank. The HOB filters always have offered several advantages over UG filters though.

One of the biggest advantages of HOB over UG is the way they trap solids to be removed. A UG filter needs to be cleaned with a gravel cleaner to remove those solids, and some people either can’t do so due to all the decorations or plants covering the gravel, don’t do it well enough, or don’t do it at all. A HOB filter traps all that debris in the filter compartment, which is usually very easy to remove and clean separately.

HOB filters tend to move more water and therefore filter at a higher rate than UG filters, though you can increase the UG filter flow by using a small submersible pump in place of an air stone on the airlift tube.

I’m not sure how quiet modern air pumps are, but the older style ones used to drive the UG air lifts tended to be relatively loud and “hummy” compared to the quieter HOB filter pumps.

In short the HOB filters are quite well made, reliable, and are self-contained compared to UG filters which are bulkier, harder to clean, and of course require the tank to have gravel.

Something that might work better for a small Betta tank is to not use gravel at all. That helps keep the cleaning easier, and lets you see if there’s uneaten food or detritus building up on the bottom which is much harder to detect with a gravel bottom. I’d also get lots of floating plants so the Betta can occupy himself blowing bubbles and making nests.

Thank you all for the information. Like I said, I didn’t keep bettas before so it’s a different branch of the hobby. Thanks especially for the floating plants tip, an aspect I hadn’t considered.

So, the “activated charcoal” is more or less marketing hype, providing little more than filtering surface area?

Charcoal provides chemical filtration (adsorption), but you don’t really need that unless you’re specifically looking to remove some chemicals (like, after you medicate a tank and you want to remove the medication). Charcoal works fine for what it does, but it stops doing that pretty quickly, and in a normal tank in normal operations you don’t need it at all.

Usually HOB filters come with some sort of proprietary filter material packet, with charcoal in it, and the manufacturers would just love for you to replace that as frequently as you need to replace charcoal if you’re using it. Those packets are expensive (-ish) and not necessary.

You need the bio-media (those ceramic donuts), and you need some kind of filter floss or sponge for mechanical filtration. But you don’t need charcoal at all unless you’ve got a specific task for charcoal to do.

Generally in a HOB filter I’ll use bio-media, floss (pillow filling is incredibly cheap, very effective, and easy to get), and maybe a small piece of sponge. I haven’t used charcoal in years. Most hobbyists don’t anymore (again, unless you have a specific reason to use it, then you use it and then you throw it out).

That’s what I kind of expected. It’s been my experience that activated charcoal is best at extracting money.

Just FYI - I had tropical fish when I was a kiddo in the 50’s and the HOB filters were common then.