RO water has everything basically removed. It is great and almost nessacary for some fish.
Discus being one of the fish that really thrive with RO water and water changes every 2 days.

Not really a need with 20 Africans in a tank the size you have. How much water do you change? It could be worse for your tank by not letting your bacteria build up that you need. The wood could leach for a along time. I have seen it leach for a year. Great for Americans not fond of wood for Africans. I try to keepmy PH at 7.8 or higher for my Africans.
I do water changes using tap water treated with Prime. 30 to 40% weekly.

This is how I do all 17 of my African tanks. Hope this gives you some insite.

Cichlidman.

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