I have a 10 gallon and 5.5 gallon tank. The 10 gallon is home to a betta nerite snail, and the 5.5 gallon currently has nothing but a few plants.
Both tanks have been set up for a minimum of 6 months, but the 10 gallon going since about a year.
In the 5.5 gallon I have diatoms. Everywhere on everything, so thick sometimes I can't even see into the tank. I do water changes weekly, about probably 20%. The tank is cycled. It's been cycled for months. The parameters are normal, 0 ammonia, 0 nitrites and 0 nitrates. Everything I've read about diatoms is that they will go away after the tank is established. They will not go away. I added some phosguard and purigen to the bettaflo filter (I also have a small sponge filter going to help with water agitation since the filter flow on the bettaflo is very minimal), but it hasn't helped at all. I have a crested java fern and a couple rosette swords (the swords are not rooting for some reason, even though it's been a few months since they were added) planted in the tank, as well as frogbit, salvinia, and duckweed floating at the top. The plants don't see to be rooting, I use fluval stratum substrate, and I dose weekly with about a half pumps worth of easy green fertilizer. The frogbit's roots in this tank grow insanely fast. In about a week, some of the roots grow to a foot long, and do it again the next week after I've trimmed them very short. But all of the floaters look really healthy and grow very fast. They are on a light timer for about 6 hours a day, medium light. When I do water changes, I just use a small airline tube so I can directly suck out as much of the diatoms as I can, it takes like an hour. I have been refilling the tank with distilled water because I don't have an RO filter, and the tap water here is high in phosphate.
In the 10 gallon my plants are struggling to grow and live and thrive. I've got several rosette swords, an amazon sword, a few small mystery plants, and an anubias. I've tried green cabomba and pogostemon stellatus in the tank, but they died within a month or two of being in the tank. I do about 10-20% water changes weekly-- I siphon out the old water into a bucket, take a sponge and wipe down algae from the sides of the tank, and then take a toothbrush to try and brush the algae off of the plant leaves because there is a green algae that is constantly coating all of the leaves in the tank, some worse than others (it was really bad on the cabomba and pogo). The plants are rooted nicely. However, the floaters in this tank are doing worse than the ones in my 5.5 gallon. The roots don't hardly grow at all, and they seem to brown and die really fast, as well as develop holes on the leaves. Both the tanks have lids, but as the 5.5 gallon isn't bothered by this I don't see why that would affect the ones in the 10 gallon, unless the condensation is different on the lid for that and drips more? I never notice a lot of condensation on the top of the lid. I dose about 1 pump one to two times a week of easy green. I also have a sponge filter with a compartment for phosguard and purigen. The light timer for this one is more advanced so I have it set up to mimic natural light, but it's also only on for about 6-7 hours a day, medium-high light.
I'm very frustrated because I want to really make these tanks look nice, but I feel too defeated between the algae, diatoms, and dying plants, to bother with it and have on many occasions thought of selling both tanks, my fish, and all of my supplies and it's only the sunk cost fallacy that has stopped me, but I dread to think I could need to spend hundreds of dollars more attempting other ways to resolve these issues, only to have them fail as well. Any knowledge and advice would be appreciated, happy to answer any questions.
Thank you so much for all the advice! There's definitely a few things I didn't know that are super helpful. I'll try to make adjustments accordingly. The only issue is that it's not feasible for me to buy dozens and dozens of jugs of distilled water frequently for much larger water changes-- do you think if I switch back to tap water or supplement with tap water it'll pose a huge issue?
