DWC with clay pebbles pH hell

johnnyfive

johnnyfive

I've been trying to stabilize clay pebbles, that I pretend to use in a DWC setup and Autopots, for quite some time now and it's giving me A LOT of unexpected work. Let me explain why.
 
I picked 2 batches of clay pebbles and I'm trying to stabilize them like this:
 
1st batch - I rinsed them A LOT under tap water and then filled a container with 5.5 pH water and  threw the pebbles there for 2 days
2nd batch - threw the pebbles directly in 5.5 pH water without rinsing under tap water
(Tap water here is around 6.8 - 7.0.)
 
There's no difference in the way pH drifts in both scenarios (pH raises to almost 7 in a day or so) and yesterday I used more pH down to get to < 5 pH on both containers. Since then the results are:
 
batch 1 | batch 2
4.3  |  4.6  (14:00)
4.9  |  5.1  (17:00)
5.1  |  5.3  (18:00)
5.2  |  5.4  (19:30)
    -- day --
5.7  |  5.8  (2:30)
5.9  |  6.0  (9:30)
 
As you can see, the drift is huge in less than a day (1.6 pH).
 
Should I worry much about the pH of the water I'm using to rinse the clay pebbles? If so, am I doing something wrong?
 
I'm using Canna Aqua Pebbles. The instructions say to rinse the pebbles in 5.5pH water for a few hours, nothing else.
 
Any great will be greatly appreciated!
 
Cheers
 
I didn't rinse mine, don't remember brand, and had no issues....
 
 
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Hello J5,
Rinsing the clay pebbles is only to get the dust off.  Nothing else.  The pebbles are full of air, and so they will finally sink if you leave them long enough in the water.  Don't waste your time....knock the dust off and go.
Peppers in hydroponics (from my own grow) is that whey they start making a lot of flowers, they really like to be basic, or alkaline, so when they start flowering, let the pH rise above 7.  When they are in veg, I kept the pH at 6,  Unlike some plants that constantly lower the pH, peppers don't really push pH levels around.  There are many issues with tap water however, and that is something that rain water guys will know....tap water may slightly basic, or slightly acidic, and may be well bufferered, or not  buffered at all.  I recommend a min. of a big ass carbon filter on your tap water...that will stabilize the incoming water and you'll have less issues with pH.  Having said that, pH for peppers is much less critical than say other flowering plants.
 
HB
 
A long time ago, I had an issue with PH fluctuations in a DWC setup with hydroton in netty pots. In my situation, after working with it and lots of testing, I found that the PH shifting was because of rotting root material.
 
I remember it all starting a week or so after I had punctured the air hose, and my DWC went for two days without air. This caused the initial root rot. I lost one plant and was able to save another (both tied into the same air pump). The plant that lived had the PH issues. the only thing that helped to SLOW the ph shifting, but not eliminate it, was to either change the water more than usual, or to hit the reservoir with a dose of hydrogen peroxide every so often. Be careful to not overuse h2o2, just a little goes a long way, and remember it will not fix the issue, just ease the ph spikes down to manageable waves.
 
The natural breaking down of the dead plant (root) matter turned into rot, and the rot cause the chemistry in the res to go astray.
 
 
Also, just for kicks, make sure the ph meter is working properly :) (re-calibrate it)
 
 
mrgg
 
 
I've found,using 5 Gal. buckets I need to not deal with PH.
I change water every week.
 
I use Dynagrow and either Folical or Witches Breaw(homade folic cal.).
 
Smoke
 
Mrgrowguy is correct. But it may not be rotting plant material. Anything in your setup that decomposes will cause an acidic shift. That can be your water, as well. Put some water in a container with no media, and aerate it for a couple days, and monitor PH. If you are satisfied, add nutrients, and check again. You have to rule out the culprit one item at a time.

By the way... Many nutrients need some sort of a drifting buffer, because they continually interact with something else. This is where it pays to use good nutrients.
 
You have problems other than expanded clay rocks if you have problems with Ph.
 
I just rinse mine, too, to get the dust off.
 
 
 
What is your ppm/ec?
 
What kind of nutrients are you using?
 
Are your nutrients self ph balanced?
 
Are you using a PH Down product? (the General Hydroponics bottle is known to cause algae growth in DWC systems, lots of posts on this forum)
 
edit - I re-read your OP, see you're using ph down. I do not know, and do not claim, that this is the reason for your plants being in the shape they are, but I would recommend a self ph'ing nutrient. I use FloraNova, for an example of one.
 
 
Just a few thoughts/questions to help diagnose.
 
 
.
 
mrgrowguy said:
What is your ppm/ec?
 
What kind of nutrients are you using?
 
Are your nutrients self ph balanced?
 
Are you using a PH Down product? (the General Hydroponics bottle is known to cause algae growth in DWC systems, lots of posts on this forum)
 
edit - I re-read your OP, see you're using ph down. I do not know, and do not claim, that this is the reason for your plants being in the shape they are, but I would recommend a self ph'ing nutrient. I use FloraNova, for an example of one.
 
 
Just a few thoughts/questions to help diagnose.
 
 
.
Click to expand...
 
Wow, General Hydroponics liquid pH down is exactly what I'm using :( The nutes I'm using are Canna's Aqua Vega A and B parts.
 
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