You would be providing a very limited lighting spectrum if you use just the actinic bulbs. Plants do use that light, but they need more than that, as far as spectrum is concerned. And, most people find a planted tank with just actinic lights looks very weird, spooky, and lacking in colors.
Any 4 bulb T5HO light is likely to be too much light for a 20 gallon tank. But, the Aquaticlife lights also have good reflectors, so with all 4 bulbs on you should have about 150 PAR at the substrate. There is no way to get enough CO2 in the water to fill the plant's needs to grow at the rate that much light demands. That is certain to lead to big algae problems. Even with 2 bulbs you will have to be very careful to get enough CO2, enough oxygen in the water, and good enough maintenance to be able to avoid algae problems.
Hi Hoppy! I just need some clarification on my lighting! What type of lighting level for plants would you call this ? Two T8s, 36 watts , 17 inch high tank (Luminaire sitting 2" Above tank, Glossy white paint at the back of the bulb), 30" length , 14" width. 4"substrate at the back 2" at the front?
Bromothymol blue by itself isn't going to work. The test reagent contains a little more than that, but the dye is bromothymol blue. API pH test kit reagent is the right mix to make this work. Or, any similar pH test kit reagent, as long as the color chart for that test kit shows that yellow is about 6.0pH and the darkest blue is about 7.6pH.