Diatoms tend to disappear on their own, but I've good luck with Nerite snails making quick work of it.
BBA is a bit of a nightmare for me as well. Slowly but surely though, I think I'm starting to dial in on getting it under control.
The first thing I did was reduce the time the lights were on from 10hrs to 7hrs. This made the most dramatic difference for me. I'm thinking about knocking it down to 6hrs, but I'm also hearing that splitting the photoperiod has a positive impact (say, 3 on, 3 off, 4 on). I just need to figure out how to set that up.
Next I increases to amount of fertilizer I put in the tank. I used to dose the recommended 1ml/gallon of PPS-Pro, but I increased it to 1.5ml/gallon a couple weeks and it seems to be helping. I'm still getting BBA, but not as much or as quickly. I might bump it up to 2ml/gallon.
As far as getting rid of existing BBA, I found that spot treating with over the counter hydrogen peroxide seems to be the most cost effective. Just make sure you turn off you filter before treatment and leave it off for 20-30 mins. I typically do a PWC afterwards as well.
Hope some of this is helpful. Good luck.
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