possible cause of PH instability in DWC?

[eaglesnester]

Using connoisseur grow in DWC. Air temp, water temp dialed in with air conditioners and water chiller. Runnin g lots of air with grow stones. My question is will Hydroton even though it has been thoroughly washed and PHed raise PH over time? Big Mike alluded to this in one of his posts in 420 Mag. I believe he said that the manufacturing process can do undesirable things.
Will peat plugs we use to start seedlings change PH as water percolates in top fed DWC? I have 4 seedlings in 25 gal Res. I am currently running 4 seedlings of White Widow and I am in day 8 with 2nd set of leaves appearing PPM 320 PH6.6 They look great roots poken out of peat plugs everywhere.

 

[TorturedSoul]

The manufacturing process? That just consists of putting little balls of clay into a rotary kiln and heating it to something like 2,200°F, lol. It's (vaguely) akin to making popcorn. On the other hand, not everything that's come out of ol' Mike's mouth is complete and utter BS, lol, so I suppose it's mathematically possible that he was typing truth that day.

I always just rinsed the dust off and "ran with it," and I never noticed any pH instability. No problems in maintaining ~5.80 pH (although I usually mixed to a little under that and let it rise slowly/naturally as the plant consumed phosphorous from the nutrient solution, then instead of trying to mess with a pH down product (assuming I wasn't changing the reservoir solution), I could just use some bloom component when I added liquid to bring the level back up.

Peat? Yeah, that can affect your pH. But I don't know if the (one presumes) relatively small amount in your system would do so to any significant degree.

There is a chart that has been posted here on the forum several times - and likely hundreds or even thousands of time across the Internet in general - that lists pH and EC (or "PPM") and breaks down what is likely for each possible combination. In other words, it can help one figure out when the plant is consuming more nutrients than water, more water than nutrients, et cetera.

If you don't make any significant changes, you check the pH of your solution today and it's fine, then check it in the morning and it has tanked... My first guess would be algal (et cetera) contamination of your reservoir, and I'd start supplementing regularly with H₂O₂ for its antimicrobial benefit (and, of course, that bust of O₂ that you get when it decomposes).

How/where/when you measure pH can affect your readings somewhat. A lot of pH meters don't have any real EMI/RFI shielding. In other words, if you are in your grow room with pumps, fans, timers, lights (maybe cheaply-manufactured ones from the PRC), et cetera when you test your sample, it could end up reading something different than what it would if you turned all that stuff off (or walked 30' away). Also, a highly aerated solution might read differently than one which has become somewhat starved for oxygen.