Ok, specs first - 10g, fully cycled (haven't measured water params in 2 months) - used API Master Test kit when I did.
Freshwater tank - had it 5 months - cycled the tank with one male Betta (now deceased), got hitch hiking Ramshorn snails (7 to 12) - did not quarantine Betta (ignorance) - tank is 78 degrees (heater).
I have a ton of live plants, small gravel substrate - use a Hydro Sponge Filter II, which I squeeze out in a small bucket of tank water monthly - Hardly any natural sunlight gets to the tank, I use a light timer - 6700K 15Watt bulb, 10 hours per day
Last water change about a week ago. Usually change weekly - most it's ever gone is a week and 3 days - I remove approx 4 gallons of water and replace with 4.5 gallons normally. I only vacuum the substrate lightly because I have 5 Sword plants and they feed on the rest - not to mention 5 other plants.
I fed my Betta once a day with Betta pellets - only 3 or 4 pellets each feeding.
He acted listless and just floated near the top of the tank. His color faded and he looked like he was actualling going gray around his mouth and head - not easy-to-see individual white spots like I've seen in pictures of Ich - but a fading whiteness ti his mouth and parts of his head.
He finally ate two pellets and ignored the other ones - when normally he'd be like a dog and eat until he couldn't fit anymore.
I'm assuming my Betta died because I didn't change the water weekly like clock-work and let it go an extra 2 or 3 days twice in a row (it had been clock work 'till then) AND that I only fed him Betta pellets. He seemed happy and he liked them so I figured why spend more money on food.
I was having an average of 2 Ramshorn snails in my tank - then a week or two ago there was a snail explosion and I counted 15 at one point. Maybe that had something to do with it. I never fed him more than 3 or 4 pellets once a day and I skipped about a day per week.
So how do I make sure my tank is suitable for any more fish? Do I have to remove everything and start all over again?
Thanks for any help you can give. This sucks and I'd like to not go through it again if I can help it.