is this unusual?

[yo420]

im growing hydro...dwc....and noticed today that if i measure the ph from a sample of the water thats in my res. than the ph is around 5.2.....but if i measure ph directly in the res. the ph is much higher around 7.....is this unusual and which reading do i go by? Do u have any suggestions on how to lower and keep the ph down? i have been using ph down but seems like i can never keep the ph where it needs to be.

[Akornpatch]

I find it strange that the sample is different from the res.

I'd go with the res numbers. You may try an R/O filter on the water supply and adjust the PH prior to adding it to the res.

[Stix]

I always find it difficult to maintain a good ph level. I usually have ph flucuation until about 4 weeks into flower. For whatever reason, my ph flucuation seems to be almost non-existent then.

It also has to do with how many plants your feeding with your resevoir. 5 gallons for every plant is ideal. I run about 2.3 gallons per plant. Therefore ph flucuation is more of a problem for me.

[yo420]

yea, im looking at a new filtration system....my water is really hard, and the its next to impossible to get the plain water down to a 5 ph...hopeing that will solves alot of problems