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ffgrowery
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You want to drop pH. You can do that with sulfur, but I personally think you shouldn't mess with it. You could pH your feed water down into the mid 6 range, but depending on your source water that pH could bounce due to alkalinity.Hey guys, I'm posting this question on several MJ forums in order to get some different opinions on this topic.
Details about the grow:
I have recently re-potted my plants into 3 gallon air-pots, filled with FFOF soil. I have watered with pH 6.0 water, and let the runoff sit for a day. Once collected, the runoff tested pH 7.8! Before you ask, I'm using an electronic Oakton EcoTester, and I've recently calibrated it.
- 4x4x6 tent
- 1000W HPS light, running %75, recently lowered to about 21" above plants.
- AC Unit set to go off at 75
- Temps have been between 68-78F (20-25C)
- Humidity between 35%-60%
- RO Water pH 6.0 with CalMag 1tbs/gallon. No neuts yet.
- Recently transplanted from 4" pots into 3 gal. Air pots.
- Soil is FFOF
This worries me because I'm afraid that the actual soil pH is somewhere well above 8, and that it might cause nutrient lockout soon. The plants are looking pretty healthy, although some of the plants are significantly shorter than others, and are slightly more yellow.
Here's what I am thinking of doing. I am all for doing a flush in hopes of lowering the pH, but instead of wasting a ton of water, I'm thinking of collecting the runoff, lowering the runoff with pH down, and running it through again. Does anyone see a problem with this? I'm considering it might be good to recycle the runoff, and put all of the nutrients in the FFOF back in the soil, while lowering the pH.
Has anyone tried this? Would this work? I'm in Cali, and with the drought, I feel crappy simply wasting runoff water. I've also heard of people adding vinegar, or lemon juice to their water in hopes to raise the acidity. Any alternatives, or other solutions to this problem are welcome!
You take several samples of the soil you want to test and mix those. You get a sample of 0EC water, test its parameters to be sure of those (pH in this case). Mix enough soil into the water to create a loose slurry. Let it set for 7-10mins (I have not found that letting it sit any longer changes readings), then re-test. Those results are much closer to what's actually happening in the root zone.
Don't chase numbers, either.
To each their own. I've used the extra lime for years with all FF soils, 1 cup per cu. ft. of medium. I don't have any problems with high or low PH. I've also given the lime advice to others having similar issues and it helped greatly. MGGI would absolutely *not* add dolomite lime in this scenario. IME dolomite lime can buffer pH up towards 8. That carbonate molecule attached to the Ca and the Mg won't let pH drop much further below 7, either, again IME. Peat would be more helpful here for naturally buffering pH towards the acidic instead of the basic.
sounds like PH is good to go bro. and i add DL before hand when i mix up a batch. it has done great at keeping my PH from getting low since i use peat base. glad its smooth sailing for ya now.Huge thanks to everyone who replied. This is my first grow so I am learning. I now realize that adding dolomite lime to the soil beforehand helps keep pH in line.
I also did the slurry method as per Seamaiden's suggestion. The pH of the water going in was a neutral 7, 20 ppm solution. After letting it sit in the slurry, the pH of the soil was around 6.8! This tells me that actual pH is probably closer to 6.6, which is pretty perfect. The plants are doing well (one grew 4" in the past week during Veg), so I'm just going to sit back and enjoy it!
Thanks again!
HAH!Carbonatated.
so may i ask you aquestion? you add no extra DL to the mix? you have no PH issues? im a promix user myself. so i was curious.I'm glad that your plants are looking up!
As with all new growers you will run into some problems big or small but the lesson here is to be proactive. Dolomite lime is a great pH adjuster to add at the beginning of your grow. The medium I use, PRO-Mix HP, has dolomite lime present in the mix so I start seeing its benefits from the beginning even before I see any pH problems.
Good luck with your grow!
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