I have currently a fairly bare 10g with only my betta in it.
I haven't tested in a while and don't plan to tonight but my tank's been running since the last week of October and usually tests with .25ppm ammonia [it ALWAYS tests this, I think it's faulty. I've never ever seen it read 0], 0ppm Nitrites, and 10-30ppm Nitrates before WC depending on how long it's been since the last WC.
Water changes: I've been a little busy and have been letting it go to 50% every 10-14 days but I typically do 25% every week.
Temp: 80* Seasonal expectations 80-86, summers here get to 120* and it's hard to keep the house cool enough to prevent spikes. My 2.5g gal spiked to 86 a few days last summer, I'm not sure what it will be like with my 10g.
Filter: Tetra Whisper EX20
Hardness and Alkalinity are a little hard. I've only tested it at Petsmart and I've had some pretty varied results. However, I know my water is hard. My 2.5g tank has tested at 120 mg/L alkalinity and 150mg/L hardness to give you an idea.
Substrate: Probably organic potting mix capped with sand or a similar set up
Plants: I'll be planting with a variety! Currently I have marimo moss balls and an amazon compacta.
Note: My betta is mostly dragonscale and his scales have started to grow over his eyes, causing some trouble with his eye sight.
Ideas: I've considered fish from Endler's Livebearers to harlequin rasboras to neon tetras. I'm not a fan of tetras at all but I'm considering them for their size. Ideally, I would like a small school of 6 of something. I also plan on getting a nerite snail.
Secondary idea: Split the tank and have two bettas with 5g each plus a nerite snail. The downside to this is that it definitely messes up my decorating ideas and I'd have to split some of Kirei's favorite hides with the new betta since they wouldn't all be able to fit on one side, plus all the regular stuff like spread of disease.
Any suggestions of small fish that would do well in my tank, given the pH and temperature in summer? Should I scrap the other fish idea and just split it for another betta? I would love another betta but I'd really rather not split it if I can find a more likable option. I've been searching for the right match for months. I can research them, but I need some ideas of what to look up. Help.