Lime or cal mag what is better

Hey guys I am just about to finish with my first grow. I have another 7 plants going I am having trouble keeping my ph in soil at acceptable levels always struggling with low ph. I am using Ro water that finishes at 7ppm. I struggle with figuring out how much cal mag to keep my plants happy. I have read about using lime (dolomite) to raise ph there is also calcium and magnesium in the lime. Question can I top dress my plants with lime and forget about the dam bottle of cal mag. If not some pointers on how much cal mag I should be using would be appreciated. 4 plants are in straight happy frog and the other 3 are in a mix of happy frog and ocean forest.

Ideally you would mix the dolomite lime into your soil. You can top dress, but that’s more of an emergency action. The lime will eventually get hard like concrete from being watered. Dolomite lime will add some calcium and magnesium though, and help buffer ph.

The big difference here is usually between being organic or synthetic. If you’re using other synthetic nutrients I don’t really see a reason to get away from the calmag. And you can flush your medium to get root zone ph up. If you’re trying to stay organic, then you can even use the lime suspended into water and apply it that way.