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Waterfall Type RDWC PH Dropping Like A Bomb

A friend of mine called me up the other day and his ph keeps dropping down to the red / orange zone of 4.0 to 5.0ph. He said he has tried adding ph up (more than ever needed) and also flushed multiple times and it just keeps dropping. I checked everything over for him and his nutrients are perfect (ppms) and everything seems fine.

The only thing I could think of is that his fill hose which runs from the reservoir to the plants is a clear hose. The hose is around 15 feet from the res to the last bucket (he is rdwc with waterfall type setup) and the nutrients that run through the hose are exposed to the powerful MH lights. I got him to put landscaping fabric over the hose and then some mylar to see if this helps. I think this might have been what was causing his ph to drop like crazy.

Any info on this would be greatly appreciated as in if someone went through this before and know or can help??


Chris Scorpio

Member of the Month: July 2018
Ya ......same old thing...need info and pics... And basically not practical in the 3rd party trying to help him

What nutes and strength
Any enzyme cleaners
Any Goopies in water
How often does he rezz change
Tap or RO water
Any light leaks into buckets, you already mentioned the clear hose..that's bad

You know the drill...help us here
yea i went over everything with him its been around 3-4 hours since i got him to block up the hose and got him to put a little ph up in to get it to 6.0 and when i tested the system it seems stable so far. i guess he will have to wait until tonight or tomorrow morning to know for sure.

- the only thing he uses is floraseries and he is running them from a custom chart i made which is around 40-50% strength.
- his roots are perfect creamy white.
- tons of oxygen - no light leaks in res or buckets.
- he is using tap water but he has a well that has around 30 ppm so it is probably the cleanest water in the world (lol)
- this is his 4th grow and everything has been a copy paste of every previous grow except before he had black vinyl tubing for the hose but he couldn't get any this time so he went for the clear vinyl hose and forgot to block it up.

i think that was the culprit but time will tell i guess.

No Pain

Well-Known Member
what stage of the grow is he in .

From what I gathered his solution running through the hose was exposed to the light ? That would be a big nono and im going to assume that he isn't using a chiller . I would take a close look at the hose and make sure there isn't anything growing in it or around where it enteres the bucket . If there is discoloration of any kind I would suggest changing it completely and running some h202 through the system .

ph dropping is generally feed or bacteria related … if its the same strain and its the fourth grow and every grow has been copy and paste and the system is running the same with the exception of what you stated I would be leaning to that being the issue as you stated and their are pathogens present in the system .
he is about 1 month into veg. he don't have a chiller but he has it in his basement and it is very controlled. the nutrient solution never goes below or above 64 and 69.

i just got back from there and since i got him to put in the ph up it is still holding strong at around 6.2-ish.

i will update tomorrow morning for myself and others with this solution (blacking out the hose) for reference if that was the cause or something else.
he is still having this problem. some things to go over with a checklist i had done for him.
1. his water pump hose was clear and i blacked it out for him - no change ph still dropping.
2. i also got some black rubber and cut them for him to put around his net pot / bucket lid. no change ph still dropping.
3. his temp / humidity all perfect
4. water temp perfect.
5. i went through his grow journal and reviewed everything and it really is a copy paste of his previous grows.

however after questioning him about some things (i know no pain you mentioned bacteria or pathogens could be the issue). i asked him about his hoses and water pump and he said his hoses were brand new but his water pump was used in a previous grow from about 6 months ago. (he has a few of these pumps) but this pump that is in this grow he said he forgot to clean it and it has been sitting in a bucket from the time he pulled it from his grow 6 months ago and it has been in this bucket wet since then.

so what i got him to do this morning is empty his res and put in around 20 ml per gallon of h2O2 and will get him to circulate that through his system for a few hours. and then drain and repeat again for a few more hours. after the 2nd flush with H2O2 i will get him to do another 2-3 flushes with pure water and then finally top up tomorrow with some bennys like tarantula or hydroguard.

if anyone has anything to add or suggest please do so.....

also his plants look amazing the roots are all creamy white and very healthy and all the plants are bushy and green. you would never say there is any problem at all.

please note as well - his meters are working correctly plus i tested with mine to double check and i used 2 different types of liquid ph testing and all show 4.0 ph -ish.
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