Reddit mentions of AquaCity Corner Filter Aquarium Fish Tank Internal Air Driven Filter with Media XY-2008

> My question is should I add a heater and small sponge filter or will the heat shock him now since he’s acclimated to room temp water for so long?

If you're worried you could get an adjustable heater and slowly increase the temperature of the water over the course of a week. It's super worth it to spend the couple extra bucks on an adjustable heater anyways.

For nano aquariums I personally love this heater: https://aquaforestaquarium.com/collections/heaters/products/copy-of-archaea-mini-aquarium-heater-25w-ultra-slim

It's really tiny and the heating adjustment is along the wire so you don't have to stick your hands in the tank.

As for the sponge filter, you should be able to just start using it. It might take the betta some getting used to. What sponge filter were you considering? You might consider one like this that has media for good bacteria growth: https://www.amazon.com/dp/B00HSCB9GC/ref=psdc_2975472011_t5_B00KZJYC9G

> So another question is how long is their lifespan in a larger heater tank?

In ideal conditions like 5 or 6 years, but you can get up to 10 if you get lucky. They do fine in non-ideal environments and are extremely adaptable animals, it's just that they're more susceptible to diseases in colder waters. Never forget that your personal experiences are anecdotal evidence! Giving your fish an optimal environment will make both of you happier and isn't all that expensive if you spend the time to plan things out.

I have discovered a great little sponge filter which allows you to put in ceramic beads to host good bacteria. Currently I have one in my 10 gallon with a HOB that I occasionally turn off.

https://www.amazon.com/Corner-Filter-Aquarium-Internal-XY-2008/dp/B00HSCB9GC/ref=pd_lpo_vtph_199_bs_img_1?_encoding=UTF8&psc=1&refRID=1RZTNWYQA649ZNXA71YV

The biggest factor that made me buy it was that most of the reviews were from betta owners with plenty of photos to back it up. So if you get that you will also need an air pump and the tubing. I use the recommended Tetra air pumps for 10G.

You will also really want a heater, betta fish prefer roughly 78f degrees. You will also want a substrate, I have noticed my betta fish have preferred sand over gravel. If you put some driftwood in there, it will lower your PH. Certain rocks will increase you water hardness. Lastly, get an API water test kit;

https://www.amazon.com/dp/B000255NCI?aaxitk=MfNb8FLf9eGj3GLSaNDlFA&pd_rd_i=B000255NCI&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=3525547702&pd_rd_wg=8L5hB&pf_rd_r=95NS5B0QQWVRY2D3W4V0&pf_rd_s=desktop-sx-top-slot&pf_rd_t=301&pd_rd_w=FvEoY&pf_rd_i=api+water+test+kit&pd_rd_r=fea43153-5be8-4228-a143-71acc8c606de&hsa_cr_id=2853308870301

Stay away from test strips.

Well, about the heaters burning fish, pretty much everyone who keeps tropical fish uses them. The risk of a faulty heater is pretty low, and overall it's better for the fish to heat the water than leave it room temp. As for the fish, bettas do well in small tanks, are active, look good, are easy to take care of, and are not timid. Care is pretty simple, just feed a high quality food made for bettas twice a day. Overfeeding is probably the most common mistake, so if you see any uneaten food remove it and feed him less in the future.

My advice for a betta would be grab a tank in the 2-5 gallon range, a 25w heater with good reviews (Amazon has tons of heaters), and a quiet air pump and corner filter. I use this filter for my betta, and it works great. Keeps the water filtered and oxygenated all at once. You'll also need some aquarium decorations to give your fish places to hide. There are tons of options out there, so grab whatever you think looks good. Type of gravel doesn't matter much either, just make sure everything in the tank has smooth edges or your betta can tear up his long fins.

Also you might want to put in a few natural plants. Anubias barteri is very easy to care for, doesn't need much light, and your betta will appreciate having places to hang out.

something like this:
pump
sponge
air tube

A small sponge filter or corner filter (this is the one I have) works well with a 5 gallon tank.

As for the temperature difference, acclimate him for 15-30 minutes before you put him into the tank and he should be fine.

Here are some good airpump + sponge filters:
most sponge filters are just sponge, though there are a couple that also contain ceramic rings or other biomedia.

here's a sponge filter that'll work for tanks up to 5 gallons.

If you do end up with a larger tank, this sponge filter has more filtering capacity. (you can also use this in a smaller tank, but it'll take up a lot of space)

For both filters you'll also need some airtubing, an airpump (other brands are also fine, but I like this one), and a valve(this one is a 10-pac, but you get the idea, here's a single corner version). If you like being extra safe, you can also get a checkvalve, to make sure your tank doesn't accidentally drains.

Good recommendation. Something like this will work as well.

Corner Filter Aquarium Fish Tank Internal Air Driven Filter with Media XY-2008 https://www.amazon.com/dp/B00HSCB9GC/ref=cm_sw_r_cp_api_Y21czbT0G0ZNV

Just make sure to rinse the media every so often

Keep it until it's falling apart - same as the sponge. It should take a long time, perhaps years. Just clean them periodically. The only things you need to replace regularly are the optional filter components: carbon every 3-4 weeks and loose filter floss as needed.

I've been running the Aquaclear 30 on a tank for 16 months and the sponges and ceramic are still in great shape. I keep two sponges at the bottom and two bags of ceramic on top. No carbon. I've replaced the prefilter once.

Doubling up on the media is beneficial in a couple ways. First, it's extra room for bacteria to grow. Second, once it's seeded you can take some if you need it for a new, hospital, or QT tank.

For instance: Last month I set up a small QT tank and instantly cycled it by taking some of the Aquaclear 30's media. I used this $5 filter with this $7 air pump plus some airline and the tank was up and running. I replaced what I took from the 30 with fresh media and the next time I need another tank I'll repeat the process. 😀

Here it is on Amazon

I use the corner filter. You will need to get an airpump with it, but you should be able to adjust the flow with a valve in the tube.

Some people will add Seachem Purigen to the bottom layer below the sponges for more chemical filtration, but I personally don't. I have a 10 gallon, planted, low-tech tank and only use Purigen if I need to remove a medication. I use the Tetra Whisper airpump to drive the filter, and I dose my plants with Seachem Flourish Excel.

It's not really gonna grow biobacteria on anything but the very surface of stuff with just the bubbler sitting in there.

Whether or not it will support enough bio-bacteria just on the surfaces of the tank is gonna depend on the size of your tank, how much you feed, how much you clean it, and how big your air pump is. You can't really know for sure without testing the water periodically after you remove the sponge filter since there's too many factors to take into account. It's possible it is enough, but nobody can accurately say for sure.

Could you try a corner filter like this instead? https://www.amazon.com/Corner-Filter-Aquarium-Internal-XY-2008/dp/B00HSCB9GC/ref=sr_1_4?ie=UTF8&qid=1500855910&sr=8-4&keywords=corner+filter+aquarium It works similar to the sponge filter but everything is enclosed in plastic so they can't eat it. I've used them with just gravel in them before. Or you could try to do similar with PVC pipe like u/VolkovME mentioned, but unless you already have PVC lying around it's probably cheaper/easier just to buy a corner filter.

This size of sponge filter is fine if you're only keeping Bettas in the 20 gallon. Granted the ones I linked aren't "corner" filters, but at that size, the round base prevents the filter from sitting flush against the sides even for the corner cut sponges.

Corner cartridge filters in this size will also work.