Need help to improve shrimp baby survival rate
I have a 3 gal shrimp tank that has been up and running for about 5 months now. Generally things are fine and nobody dies. A month ago, I had two Taiwan bee shrimp get berried, and the first hatched the eggs about a week and a half ago, and the other a week later. Yesterday and the day before, I found a total of three dead baby shrimp. I don't know what killed them off, and one of them was a slightly larger size, so it must have already gone thru one molt or more. There are a few issues that I could think of:
1) regarding "biofilm", is there enough? There is a moss tree in the center, where I assume most of the shrimp are hiding. There is also some algae on the side and back wall, but not a whole lot visible in the rest of the tank. Ever since the babies came out, I have been dosing the tank with Bacter AE once per two days. However, there has recently been an outbreak of (I dunno, aquatic aphids? They are tiny dots less than 0.5mm large and sort of look like a tick) which have also been eating the algae.
2) Most of the baby shrimp that I see are inactive and just standing around, which I think is a bad thing. Occasionally there will be one that is actively grazing and trailing a string of poop, but that's maybe less than 1 in 5. (Maybe the rest are hiding in the moss tree grazing, I dunno)
3) Attacked by rhabdocoela? No, they are not planaria. Sometimes one will approach a baby, and the baby will flick and move away, but other times the baby shrimp seems to give up and let the rhabdo crawl all over it.
4) Got something stuck on its claws and starved? One of the dead shrimp did seem to have a blob of something stuck to it, and I think it is due to bits of food that fell into the substrate or maybe bits of decayed Indian Almond leaves that got moldy and made a sticky substance. My aquarium does seem to have bits of this here and there, and it is sticky enough that it can lift up pieces of substrate (little 2mm balls of UNS Controsoil).
5) Water parameters? Not to be too TLDR, but the parameters are suited for caridina shrimp, no ammonia, and the only concerning parameter is the NO3, which started off at 5 ppm a month ago, but recently rose to slightly below 10ppm, maybe due to all the extra feeding I was doing with Bacter AE and Shrimp Baby. I did one water change and turned up the lighting some more to encourage more plant growth. (However, it seems that if I make the light too bright, my neo shrimp become inert)
Anyway, that's all I can think of for now.