Simple ph question

Well I thought it was but I can't find much on it. Im using promix HP and I'm going to water till I get runoff tonight and check the ph. If it needs to either rise or lower can I do that by either raising or lowering the ph of my feedings? Or is it somthing that has to be flushed out to be corrected?

Jeffro420 said:

Well I thought it was but I can't find much on it. Im using promix HP and I'm going to water till I get runoff tonight and check the ph. If it needs to either rise or lower can I do that by either raising or lowering the ph of my feedings? Or is it somthing that has to be flushed out to be corrected?

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You only need to flush if you missed it for a while and it's way off and the plants are showing significant signs. Otherwise, you can feed over PH'd (4.5-5.5 to lower your ph or 7.5-8.5 to raise) followed by a bit of 6.5 (or 6.2 or whatever your target is) PH water/nutes to ensure no part of the soil stays over adjusted.

Note, don't adjust too much too fast unless the plants tell you to. If they look healthy, either don't adjust at all or only adjust by .2 or less per watering.

Personally I've never found a run-off test to be an accurate test. Do a slurry test to get a accurate measure of what the root zone pH is.
Just remember if you flush you will also be flushing you're soil buffer that was in the medium.

only time I've been concerned about runoff is either when I had a problem with plants (in which case run off was around 2400ppm) or when I was flushing to finish and trying to get it below 200ppm

Jeffro420 said:

Well I thought it was but I can't find much on it. Im using promix HP and I'm going to water till I get runoff tonight and check the ph. If it needs to either rise or lower can I do that by either raising or lowering the ph of my feedings? Or is it somthing that has to be flushed out to be corrected?

Click to expand...

Just ph the water/nutrient solution. I ran promix at about 6.3 the soil is prebuffered anything above 6.5 will give you trouble. Use a tds meter to check the runoff. You want your parts per million or the runoff to be close to what your putting in. Watch for the x10 on the meter. Seen a lot of guys say the ppms are only 150 but I'm feeding 300 or what ever. They didn't notice the times ten. this is what i used it was $14 at amazon http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY

Man don't get caught up in this mess. It's a road trip to no where.

Thanks for the response guys. I've got a blue labs ph tester. I have been running half strength nutes for the last 4 weeks and ph'ing to 5.8-6.2 and I've got some leaf drooping and slight yellowing but it could be from under feeding.I was just trying to check everything over.

Dr.Pecker said:

Just ph the water/nutrient solution. I ran promix at about 6.3 the soil is prebuffered anything above 6.5 will give you trouble. Use a tds meter to check the runoff. You want your parts per million or the runoff to be close to what your putting in. Watch for the x10 on the meter. Seen a lot of guys say the ppms are only 150 but I'm feeding 300 or what ever. They didn't notice the times ten. this is what i used it was $14 at amazon

http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY

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This… I ran Promix for a couple years (switched to Happy Frog but it really didn't change anything except lighter feeding in veg) I ran ph of 6.3-6.5 in veg (would intentionally do a 6.5 every 3-4 waterings and 6.1-6.3 in flower never had issues.

Jeffro420 said:

Thanks for the response guys. I've got a blue labs ph tester. I have been running half strength nutes for the last 4 weeks and ph'ing to 5.8-6.2 and I've got some leaf drooping and slight yellowing but it could be from under feeding.I was just trying to check everything over.

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crank up the nutes alittle make sure no dry spots in soil a little bit of runoff is good just so u no there is no dry spots in pot u don't want promix to complety dry out.

Jeffro420 said:

Well I thought it was but I can't find much on it. Im using promix HP and I'm going to water till I get runoff tonight and check the ph. If it needs to either rise or lower can I do that by either raising or lowering the ph of my feedings? Or is it somthing that has to be flushed out to be corrected?

Click to expand...

why are you checking the run off as that's the most stupid'est method ever

promix has buffers init if u water is not right u will have problems ph water5.8 going in u should b fine kiss my freind

Ok watered last night and this morning things looked alot better. I ran ph of 6.4 in that watering. So I'm thinking my ph was too low. I'll continue to run slightly higher ph and see how that does. I can't seem to get runoff unless I water like a gallon or so into my 5 gallon pots. So i could never test ph.in runoff.

Jeffro420 said:

Well I thought it was but I can't find much on it. Im using promix HP and I'm going to water till I get runoff tonight and check the ph.

Click to expand...

Premier Horticulture recommended 5.9 when asked. I used 5.8-6.0 in veg. And, 6.0-6.2 in flower.

For runoff ph, google for "NCSU Pour-Through Runoff Method." That's the most accurate way to measure runoff ph. If you think about the two factors involved in that, you'll realize why casual runoff isn't an accurate reflection of the fertigated soil's ph.

if you really want to to get into soil ph, spend $70 on a Control Wizard Accurate 8 soil probe. You have to use the whetting cloth each time before use (use 0000 steel wool when that wears out). And, leave it for exactly 10 minutes each time before reading. It's handy to see how the ph changes over time (not just when saturated).

A lot of this is standard-answer stuff. It's too bad we don't have a wiki or something to condense standard info into.

Jeffro420 said:

If it needs to either rise or lower can I do that by either raising or lowering the ph of my feedings? Or is it somthing that has to be flushed out to be corrected?

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Yes, I sometimes fed higher ph to raise the ph. You can also sprinkle some fine dolomite lime on the top, rake it in to the soil, and let it water in. But, chasing ph is frought with problems.

I strongly advise you to feed enough volume for 20% runoff. Usually the ph problem (for me) was due to overfeeding, salt buildup. 20% runoff can help prevent that from happening. Monitoring your runoff ppm will help you see that condition arise and allow you to dial in your nute strength and runoff volume.

I don't think "no" runoff is ever a good idea. You should mix more volume.

I ended up switching from soilless to soil (but still predominately Pro-Mix HP). See my sig for details. I think it works better than hydro nutes in soilless.