A few months ago I removed the stone top layer of substrate from my 20H and replaced it with a sand. The under layer is almost completly laterite. Once the tank was replanted and the sand had settled. There was an algal bloom(as expected), however plant growth was very timited. Even specied such as hygro. polysperma remained stagnant. Green hair algae is a constant problem even two months out. Plants are growing ut not enough to keep algae at bay. There is about 100w 6700K of light on the 20H tank. Does anyone else know of any reasons for the anemic plant growth?
That much light without CO2 only feeds algae, no surprise. You need to reduce the light to no more than 50w without CO2. How are you fertilizing? starving the plants also encourages algae to grow.
Truvu 100g Flourite, wet/dry, AHSupply 302w PC, PinPoint controller 10gallon15w T6+15w T8 55gallon40w T6 ODNO4x, no CO2. Discus grow out.
10gallon Tonina tank, 2x15w T6 ODNO 4x
I will do aquascapes after I collect all the plant species and grow them to perfection.
Get the nitrate test kit anyway, you need it, but I think no CO2 is the source of your problems. Even though it is a high tank, 100 watts is still a lot of light over 20 gallons. How are you getting your 100 watts (PC, ODNO, NO ...)?
From my experience, adding ferts will make it worse. Your plants are not able to grow because you lack co2. With that much light, your plants need the extra co2 that your fish cant provide. Your plants wont take up the extra ferts, but algae will.