What fish can go with paros? And how to go below ph 5?

Hi there,

i’m new to these fish or blackwater for that matter, and while this forum seems dead, my hope dies last. My tank has been cycling for about 6 month now, and i’m still having more algea then i’d prefer. Are there any algea eating fish or shrimp that survive the extreme conditions the pacos need?

And how do you get below ph 5? I’m hovering around 5.5 although i’m using wood, leaves, peat and pure RO water.

Anyhelp is welcome
Ty