no CA reactor.. what's the best way?

If you drip ph during the day your ph may fluctuate to high, not too low. During the day like otty said your ph will go up because your corals and other life in your tank is photosynthesizing, basically anytime your lights are one. At night time your ph drops as all the life stops photosynthesis. A reverse daylight schedule on your fuge will also help to keep the ph stable. In my case my ph on my tank still drops about .15-.20 usually it is 8.3 and goes down to as low as 8.1 sometimes right before the display lights come back on.
This is why some people run their ATO through a kalk reactor only at night. But you have to figure out your evaporation rate, and then you need to setup timers. The kalk mixing timer needs to be set different than the the top off timers. You don't want water going through the kalk reactor when the mixing pump is on. And like I said before, you don't want your ATO "catching up" all at once, so you would want the initial "ato on" to be a very short time depending on your flow rate slower flow would allow for more ON time, where faster ATO flow would need less "ON" time.

Hope this is helpful.

 

If you have heavy calcium demands, say with SPS, you won't be able to maintain calcium levels with kalk alone. You simply don't evaporate enough water each day to replace the calcium that is used through kalk alone.

I have two tanks. The one that is a couple of years old has a kalk reactor hooked up to an ATO system. Before that I dripped kalk daily to replace evaporation. pH has never spiked.

My other tank has kalk in a bucket hooked up to an ATO system. pH has never spiked in either case.

Kalk is just calcium hydroxide. The 2 part systems also replace calcium carbonate. When using both kalk and 2 part, you probably won't use as much 2 part, and also probably won't need as much of the alkalinity component of the two part. In my tank I dose 2 part 2 times a week and use about double the dose of the calcium part as the alkalinity part. When I started using them I tested alk and calcium daily to determine size and frequency of the dosing.

 

Darthclownfish, Calcium carbonate is the bond of calcium ions and carbonate(ALK) ions. Also, do you use a RO/DI? It is possible that the tap water in your area is hard, meaning it already has "alkalinity." If you use that for your top off water combined with limewater or kalk you would be giving your tank more of the ratio of alk than you would be giving Calcium, which means you would need to supplement more calcium to keep the "balance" of your tank.
Do you run an electronic ph meter? If you dose 1 gallon of limewater to a smaller tank, lets say 80 gallons total volume, in a short time would notice a significant jump in your ph. The ph would go up 0.6 to 0.7 higher than the original ph. It only takes a few hours to fall back down, but this is obviously by far TOO much of a swing. If you use test kits, you may have never tested ph after soon after dosing your kalk.

If you have a problem with not being able to evaporate enough water to maintain your calcium and alk levels via kalk you can add a small fan to your tank, this will substantially raise the amount of evaporation. A fan also will help with cooling the tank at the same time.

Lastly, here are a few articles for your reading drewspuppet, and darth you may also want to take a look.

What Your Grandmother Never Told You About Lime by Randy Holmes-Farley - Reefkeeping.com

Chemistry and the Aquarium

A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com

Advanced Aquarist's Online Magazine - Chemistry and the Aquarium: Calcium

It may take a while to read them, but they will definitely make everything much clearer. At first may feel a little overwhelming, but you'll get it by the time you are done reading.

Good luck with whatever you choose.