The figure you need is 1.68 deg Clark. The two hardness units used in fish keeping are ppm and dH (fish profiles will use one or the other).
1.68 Clark = 24 ppm and 1.3 dH.
That's not just 'soft' it's 'very soft'.
This is perfect for soft water fish, which also prefer a pH below 7.0. I would stop using the coral sand and make sure you keep soft water fish.
Seriously Fish is just about the best website for fish research. They have two species called hoplo, is yours one of these?
There are others as well. But the two on Seriously Fish appear to be hard water fish, which are not really suitable for your water - or compatible with the other fish.
1.68 Clark = 24 ppm and 1.3 dH.
That's not just 'soft' it's 'very soft'.
This is perfect for soft water fish, which also prefer a pH below 7.0. I would stop using the coral sand and make sure you keep soft water fish.
Seriously Fish is just about the best website for fish research. They have two species called hoplo, is yours one of these?
Search Results hoplo — Seriously Fish
www.seriouslyfish.com