DWC PH Help.

I just had an idea and I was wondering if anyone could tell me if it would work or not.. I am having an issue with my PH climbing after I do my weekly res change. I mix my nutrient solution and adjust ph to around 5.8-6.0 and within 24 hours it will climb all the way to 7.0-8.0+

So here is my Idea.. If I am to not adjust my PH at res change and just leave it low around 4.0 will it naturally climb to around 6.0 where I want it? or is this just a bad idea and will stress the plants?

From what I have been reading this big PH climb is normal for Fox Farm nutrient line.. But I have already spent the money so I am stuck with the FF until it runs out.


My set-up
Two 5 gal "Lowe's" water coolers
Two 4" air disc's
General hydroponics dual diaphragm air pump
400w MH in 6" cooling tube /w refelctor hood
Fox Farm nutrient line, Going by the FF hydro feeding chart
RO water only

Mabey the RO water is the reason. Lack of PH buffers.

I had exactly the same problem but I found a solution from others here on RIU, although I can't recall what thread or who said it. I use tap water so first I fill up several containers & let's them sit open for at least 24hrs to dissapate any chlorine. Then I use another res same capacity as my grow res to premix my nutes (15 gal) and put a pump in there to circulate it for another 24 hrs at least. That's it...I never even check the ph until later & almost never need to adjust it.
Then I simply pump out the old nutes into buckets from my grow res when I do a change & pump in the new stuff from the circulating res....wait 12-24 hrs & check ph again. If low I add a little straight water(my tap water ph is always about 7.0) if high I adjust using buffering solution diluted in water. During the first few days the ph might flucuate a little but stabilizes within a day or 2. This method is much faster & easier to stabilize ph than when I used to add nutes directly to the res. I typically just add ph adjusted water until the next nite change (every 14 days)
I think the main problem is that the nutrients need time to buffer the ph and stabilize it. When you put the nutes directly into the res it throws the ph all out of whack & you end up chasing it around with buffering solution to nail it down. Try premixing your nutes first & waiting a day to change them out, then adjust if needed. I bet you will soon be using much less buffering solution & will find yourself needing to worry about the ph less and less.

Thanks midnitetoak I'll give that a try.

Wow. Thats a ton of work for a weed. I would have to have 300-400 gallons sitting out and mixing. I started a new rew two nights ago and set ph at 5.7, last night it was at 5.8. Water+nutes+additives then adjust ph.

Yeah its a bit of work. I only need about 15 gal to fill my res so I only have to carry 3 5g buckets around to change out nutes/res water. I can see how this is not feasible for a large system but for a system under say 20 gal it does help stabilize ph by allowing the buffers in your nutrients time to work. Just circulating your nutes for a day or 2 before a res change does make keeping the ph in the proper range almost effortless. Sometimes I go a few days without even bothering to check ph because I know its right around 6.0, perfect for dwc...

I use 5gl buckets & GH nutes,when I use hydroton I rinse it very well,then when I pit the nutes in PH is 5.8.
I use to let it set out to get rid of chlorine then someone told me I didn't have to,I tried it,don't need to.
Anyway I forget to check PH sometimes now.It's important to get it regulated quick 'cause it will make the leaves wrinkle
and the stems grow long.GLTY

I PH my solution to around 5.3-5.4 going in, it's usually around 5.7 the next day and I adjust down. This seems to be the best way to keep the PH near optimal, aim a little low at the start and adjust down every day after that.