I am growing in flood and drain buckets with hydroton and using GH nutrients. I use RO water and just changed the filters and membrane in the last 3 weeks. Normally I can control my ph by the strength of my nutrients and when everything is good the ph slowly climbs and the ppm stays about the same. I have been growing a good while and have not had any real difficulties.
For the past few months my ph has been dropping very rapidly and I cannot figure out the cause as nothing has changed. It drops in the veg res as well as the flower res. The roots are white and look as they normally do. Res temps are in the high 60s to low 70s and air temp is mid 70s. In veg if I set my ppm around 400 the PH normally comes out at 5.9. When I check it the next day it is around 4.9 and ppm drops because 400bis a pretty low note level and they are wanting more. the day after the PH drops to around 4.0. I have been using ph up like crazy to try and combat this but I really don't like using anything to adjust the PH and I know I shouldn't have to. If I set the ppm where I normally would, around 750, I get the same result with the PH drastically dropping.
 
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I am growing in flood and drain buckets with hydroton and using GH nutrients. I use RO water and just changed the filters and membrane in the last 3 weeks. Normally I can control my ph by the strength of my nutrients and when everything is good the ph slowly climbs and the ppm stays about the same. I have been growing a good while and have not had any real difficulties.
For the past few months my ph has been dropping very rapidly and I cannot figure out the cause as nothing has changed. It drops in the veg res as well as the flower res. The roots are white and look as they normally do. Res temps are in the high 60s to low 70s and air temp is mid 70s. In veg if I set my ppm around 400 the PH normally comes out at 5.9. When I check it the next day it is around 4.9 and ppm drops because 400bis a pretty low note level and they are wanting more. the day after the PH drops to around 4.0. I have been using ph up like crazy to try and combat this but I really don't like using anything to adjust the PH and I know I shouldn't have to. If I set the ppm where I normally would, around 750, I get the same result with the PH drastically dropping.
Any chance its a new (possibly bad) bottle of nutes? HUmic/fulvic acid is used to buffer pH, might consider getting a bit of that.
 
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I am growing in flood and drain buckets with hydroton and using GH nutrients. I use RO water and just changed the filters and membrane in the last 3 weeks. Normally I can control my ph by the strength of my nutrients and when everything is good the ph slowly climbs and the ppm stays about the same. I have been growing a good while and have not had any real difficulties.
For the past few months my ph has been dropping very rapidly and I cannot figure out the cause as nothing has changed. It drops in the veg res as well as the flower res. The roots are white and look as they normally do. Res temps are in the high 60s to low 70s and air temp is mid 70s. In veg if I set my ppm around 400 the PH normally comes out at 5.9. When I check it the next day it is around 4.9 and ppm drops because 400bis a pretty low note level and they are wanting more. the day after the PH drops to around 4.0. I have been using ph up like crazy to try and combat this but I really don't like using anything to adjust the PH and I know I shouldn't have to. If I set the ppm where I normally would, around 750, I get the same result with the PH drastically dropping.
by no means am i a water guy,but i do use pumps for making tea,might be stupid answer but ive had it happen to me also,my pump was getting hot after a few days and air flow had slowed down,went to check the tubes ,all good,picked up pump and burnt my hand it was so hot,i replaced the pump and all good and i keep mine outside,might check,some even have filters in them im told
 
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correct me if im wrong,but my water ph goes up with bubbling tea,when i shut pump off and come back hour later the ph has dropped that why i mention the above
 
As far as nutes go, that is about the only thing that I have not yet checked. I went and bought 3 new bottles of nutes today. I mixed the old in a 5 gallon bucket and mixed the new in a 5 gallon bucket. They had the same ph of 5.8. I am going to check them both in the morning and see if there is a change in one or the other.
As far as the pumps go, they seem to be functioning properly. The issue is also with all of my nute reservoirs so that should mostly rule out a pump failure.
The ph meter is functioning correctly and recalibrated today.
 
I checked the bucket of old solution and new solution and they both had a ph of 5.7. I'm thinking it has to be something in the system that is decaying but whatever it is, is in all 3?
 
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If i had to guess off the info provided, I would say its your KH (carbonate hardness). The reason I say this is because you changed your R/O filters and that will cause them to be more effective. Basically giving you a KH of 0 and making your PH very unstable as it has no buffering capacity. If you head down to a local pet shop you can buy a KH test kit. If you get your KH to high it will be difficult to lower you PH as it has a high buffering capacity, that is why ppl with hard water use R/O to begin with. Probably the easiest fix rather than reconstituting your R/O water is to use 3/4 R/O and 1/4 tap (ratio depending on your PH out of the tap) or reconstitute your KH with potassium/calcium carbonate.

I'm guessing your nutrients are balanced for tap water and not specific to R/O so would contain less carbonate than you require to provide a stable PH and your PH is crashing..

Just my guess.

Dan
 
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