Hi Lawrence,

Welcome on board. What type of plants do you hv? If your tank just with mosses, liquid fertilizer will be enough. You can get the Sera, ADA, Dennerle or JBL products. The rest...not so usefull. Or you can get the PMDD which is the formula mixed by member in here.

Beside liquid fertilizer, you can get the base fertilizer or those tablet/tube fertilizer which you can put inside the gravel.

Since you are using DIY CO2...it is hard for you to adjust the bubbles and find out the PH level. And how are you getting the CO2 dissolve into the water? By diffusor? by reactor?

Perhaps, you can post the pic of your tank. Let experts in here to give some comments n advices.