If i had to deal with high water PPM's, then i would start everything off at 1/4 strength, PH the water, then add to system. Check in 12 hours if PPM's have gone down or up...
If you water in a nute solution that is 200PPM for example and you check in 12 hours. If the PPM/ec is dropped just pour a small amount of water out into a cup, add more nute solution to cup then dump back into the system. If it has shot up then just dilute the nute soltuion down a bit.
The main reason i seen people get in trouble with hydro is when they loose control. Staying on top of things like PPM's, Temps and PH is key, imo. If you check it regularly and make sure its not doing wild swings then you could be fine.
From what I see here in threads, the biggest problem is that people fuss with ( control... ) too much! Once you know how your nutes react in a res, you shouldn't have to mess with it more than once or twice over the period of a week. I could go away for a week and know where my res will be at when I get back. People need to STOP messing with the PH. set it to 5.8 and forget it unless you got some wacky nutes that shoot way up after a few hours, even then, one you learn how it reacts, you shouldn't need to mess with it. If you nutes tend to spike, start at 5.6 instead and let it rise, its got to stabilize somewhere. Adding PH up or down to the res can shock your plants
Tap water is the biggest culprit in ph shift. Straight from the faucet is even worse. The chlorine may not actually be enough to bother they plants, but as chlorine evaporates, your PH changes. Everyone should at a minimum, filter then bubble there water. ph after this has been done.
PH up or down added to the res can shock your plants. The less you use/need to use them the better.
EC/PPM again, you shouldn't need to mess with your nutes on DWC/RDWC before res change, except maybe late into flowering if you have large plants or a small res- 5 gallons or less. If you nutes are getting too high, then your using too much to begin with. There is no reason IMO to use more than 800 ppms in a res. I keep mine at round 600 ppms. Think this is low? google HygroHybrid. He's be growing 1lb.+ plants for years in DWC. I've seen him use his techniques in at least a dozen different strains. None are ever fed more than 600 ppms of nutes! Nute makers want you to buy those liquid nutes! If you feel you need to run them high, 1000ppms or more, then you'd be best off using an automated res control sysem that maintains your ph and ppms for you, as they micro manage things to keep stress to a minimum.
If your using RO water and having constant ph problems, CHANGE NUTES! Just because ABC Super Nutes work for Joe, doesn't mean its going to work right for you. If your doing everything else right, then the only culprit left is your nutes. Like anything else, you can get a bad batch, but most people would never think of that and drive themselves crazy trying to figure out what's wrong.
I'm not claiming to be an expert, but I put a lot of work into learning how to do this right. At last res change my PH was 5.9. That was 7 days ago. today I tested as I'm doing a res change. It was 5.9 I must be doing something right!
