Don't dose anything until you can test for it and after testing, your tank needs it.
Cheers! Mark
Dosing is likely only required in SPS dominate tanks including many or large clams.
As an alternative to 2 part dosing... for softies and LPS, you may be able to just get away with adding Kalkwasser to your ATO reservoir in order to maintain proper Alk and Cal levels in your reef tank. If you want to get fancy, get a Kalk reactor or stirrer and push fresh top off water from your ATO reservoir through it.
If you have dosers, go with 2 part dosing. If you advance to more demanding corals like SPS down the road, 2 part dosing will always keep up. If you want immediate simplicity, add Kalk power to your ATO as directed and keep a spare $23 Tunze ATO pump on hand. However, if you advance to more demanding coral down the road, you may reach a point where Kalk is not enough to keep up with demand. Below are a couple of very helpful videos...
2 part dosing -
https://m.youtube.com/watch?v=bVI69xOb_JM
Kalkwasser dosing -
https://m.youtube.com/watch?v=KSsdxuWY0T8
...I will do 2 part I dont want to clog up my ATO.
I won't try to dissuade you just point you in the right direction
a limewater "reactor" isn't much of a thing, simple to make. Tunze even has one in their line - it's just a bottle with a few fittings. I'll look in my junk, I might have one you could try out if you are inclined.
I like to add kalk to low load tanks. IO is low, kalk pushes things closer to right.