Hi everyone its been a while since I have posted but I really need help. Its not some repeatative question on how long to keep the timer on for a drip system. I have been reading all over the boards searching and couldnt find what I was looking for so I thought I would ask. I know that you have to have your drip system on for 15 mins for 3 times a day but in everyones opinion what times during the daylight cycle do you schedule your drips to come on since my lights start at 6am and turn off at 12am. I would really appreciate the help thank you.

15 minutes three times a day is a rule of thumb that may not apply to you at all.
You're looking to irrigate often enough, at a great enough volume, to provide an appropriate average level of moisture in your root zone. Prob gonna be a whole lot less, esp for young plants which don't have a lot of leaf area transpiring water.
Fer instance, my rockwool drip gets irrigated for 27 seconds every hour and 15 minutes that the lights are on. ( I have cool timers).
If you're using a cycle timer to control the pump, just plug it into the same power strip as the lighting system- it'll cycle on first.
I don't like standard timers for drip systems- the granularity is too coarse. I'm a " lots of small feeds instead of waterlogging with a few big ones" type of guy. YMMV

Basically, you have to play with it until you get a pattern that keeps your media moist but not too wet, by adjusting how long and how often pump is on. Easier with a quicker draining medium.

You may or may not need to irrigate a little while lights are off, depending on night humidity- I never have. YMMV

Your lights are only on six hours a day?

Yea lights should be off for 6 hours for veg. 12/12 for flower. I keep my drip on 24/7 from day one , never had a problem yet. Some like to cycle but alot go all the time. It's all about what works for you. Tune it in.

My lights are on 18 hours its from 6am till 12am the next day. I was wondering what time it would be good to turn it on during the light cycle. I keep reading about the rockwool tends to stay wet for a long time and tends to build up salt I plan on putting my 1in cubes into the 3inch rockwool blocks while inside grow rocks when the roots become established and then into the eurogrower. Should I let it drip on top of the blocks or around the area towards the roots and so the grow rocks get wet too?

wassup rhizome

I always hear about peeps watering just before the lights come on, like 30 mins, thats how mine is set up. I have a recirculating drip system, a kick ass one at that.

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This is basically how we do it in the commercial greenhouse.

At home I find that if you use commercial drip equipment, 1/2 tubing and say...2gph or 4gph emitters (trial & error), you can use 15 minute on times and not flood plants, + you can also water more often, also.
Everyone doesn't have this option or understand drip as more experienced growers here. Anyway. Great answer. Might be too complicated for those who don't have multi zone digital timers. I love it.

Now I know a few people have good success dripping non stop using hydroton and only while lights on. I think maybe one watering during lights off will suffice, unless using rockwool, then you cut back a bit, because that tends to hold more dense moisture, than other mediums.

And finally whooo...long winded as usual...
The point here being. The basic answer is: Water enough to keep your medium moist (as mentioned above). You have to dial in the timings yourself by addressing the nuances of your system, and choice of medium; Through trial and error. Good luck. Look likes if you have a problem we have a few worthy "new" Or "returned" members here to guide you this Spring. And: Of course the "old guard" Peace

Damn- praise from Ceasar...

Thank you, sir.

final watering, 30 minutes to 2 hours before lights out...1st watering, right before lights on.

I just finished a tub over tub grow with 24/7 dripping...I felt like I got too much leafy foliage...I think that cutting the water at night tends to allow the plant to use more store nutrition and that equates to buddage not leafage....Peace