PH question

[piercedpunkonpot]

Im on my fourth grow and decided to start troubleshooting everything and taking a more detailed approach to my growing. I have noticed that no matter what I do to my plants (light, air temp, ect) they seem to take forever to grow and my yields are good, but for the most part small. I cant seem to get my buds to fill in densely. Im only growing 2 plants in a 2'deep x 3.5' wide x 4' tall cabinet with a 150 watt HPS lamp for flowering and 3 "150watt" (23watts) CFL blue spectrum bulbs for vegging. I have tried everything down to PH and so I bought a PH meter. I started testing everything and I see that my tap water is a perfect 7, sometimes like a 6.8, but usualy a 7 right out of the tap. When I add the recommended amount of fertilizer every other watering my water's PH changes to about a 6.7 or so. I noticed that my runoff and soil however have a reading of anywhere from 7.5-8 and I have a good felling that this is what's slowing my growth. My soil is composed of an all purpose soil mixed with additional peralite to help it drain better (i had a problem with water not draining near my last harvest). I know alot of people frown upon alot of the all purpose soils, but I have two plants vegging at the moment and want to know what I can to to get my PH at an optimum level with what I have. I have heard some people say to add more fertilizer but Im scared to over do it and burn my plants, same with lemon juice or urine. Anyone have any suggestions as to what I can to to atleast stabilize and or maintain this PH in my soil? Was I informed correct about the fertilizer or the acidic stuff? Thanx for the help everyone!:thumbsup:

[4x5]

lime "raises" ph (water it in to soil, check ph of soil), adding a drop of vinegar to your watering solution and checking ph will lower it (drop, mix, check, repeat; with vinegar, it works fast). And, you may as well use the hps and the cfls throughout the grow, bigger quicker veg, better flower, maybe add another hps?

[4x5]

you could also use sodium bicarbonate (in water, add a bit, mix, check ph, repeat) to raise the PH instead of the lime

[piercedpunkonpot]

so vinager works well? I only need to lower the PH at this point. How much vinager to water ratio should I use to lower my PH a point or two safely w/o frying my plant?

[stinkyattic]

Vinegar isn't ideal but it's better than lemon juice and CERTAINLY better than urine (guaranteed to burn the fuck out of your plants with available nitrogen).

You will have to play around a little bit. What I would do is since your runoff is 7.5 and your nute solution is 6.7, first of all flush your plants very well with water at pH 6.5 just to remove any salt buildup. And check the runoff at the end of flushing. Then make a fertilizer solution at 1/4 the strength that you usually use, and adjust the pH down just a little lower than your goal. I would shoot for between 6 and 6.3. Water with this until it runs out the bottom of the pot, and test the runoff. It should come down.

Edit: Do yourself a favor and pick up some pH down for the future. And cider vinegar is the best for your plants... something to do with soil beneficials... but I forgot what! :jointsmile:

[piercedpunkonpot]

Thanks Stinky. Ill give the cider vinager and flushing a run through and see what I come up with. What signs aside from slow growth are brought from a high PH? Anything else to be concerned with?

[stinkyattic]

Yes, slow growth isn't as dangerous as the nutrient locks you'll see when pH is out of range. You will see weird deficency symptoms, even though you are feeding properly, and that's because the plant's roots only function in a certain narrow pH range.

[4x5]

just a few drops of vinegar though, BE CAREFUL!