Keep the sponge in the 90G for a couple of weeks. Fill the 20G with 10G of water from the 90G and the rest RO. Put the seeded sponge in the 20G, and add some Seachem Stability as instructed and you should be good to go. A small box filter with some Purigen goes a long way toward keeping it clean too.
Water changes will be your best friend. Unless your source water is hard as a rock, RO shouldn't be needed. Unless these are LFS angels that were imported or farmed somewhere, the lion's share of hybrid's available privately don't need RO, and can deal withe somewhat elevated Ph and Dkh.
Water changes will be your best friend. Unless your source water is hard as a rock, RO shouldn't be needed. Unless these are LFS angels that were imported or farmed somewhere, the lion's share of hybrid's available privately don't need RO, and can deal withe somewhat elevated Ph and Dkh.