Bear in mind that it might be a combo of the reactor not doing well and not enough CO2 being produced in the first place, youd be suprised just how much it takes, and with a big tank like yours, even more so.

If you find reactors are an issue, its possible to pick up some very good glass blown 'mist' producing ones, for about $40. Well worth the investment if you cant get the DIY ones to work. Its worth trying the DIY ones first, Im all for paying for as little as possible, but i realised the amount Id spent on DIY stuff, woulda payed for alot of the equipment for pressurised anyway. If your aim is to, in the end, have a very hassle free tank, with minimum maintenence, Id urge you to look at pressurised CO2, once your setup, the actual CO2 is dead cheap.