Ph trouble, in flowering stage Help Please

Ok so heres the details

I have 2 plants under 6 42w CFL's. I have used MG soil and I had been watering with 6.5 ph water. The thing is I used SPA PH adjuster because I couldnt get the aquarium or hydro PH Down and I was advised not to use vinegar.

I did this for maybe the first month? after that I was able to find the aquarium PH adjuster and I've been using that. Everything was going well until 1-2 weeks before flowering and within a few days the PH just went to crap (5.5 area).

I had tested my run off using my digital PH testing pen, and it was around 6.3(I think I did this wrong somehow), but now I ordered a soil PH tester and it is telling me my PH is 5.5.


How can I safely raise my PH to the appropriate levels without killing my plants? They are 3 weeks into flowering (est 9-10 weeks total from breeder).

The only useful info I have found was to use Dolomite Lime and add it to your water but I have some powdered dolomite lime and I have flushed with water I mixed very well with it and the PH is still low. My current plan is to go back to the store to get the pelleted type and grind it to see if it works better and just use small amounts to avoid killing my babies.Also I have conflicting info on how much to mix per gallon OF WATER.

Thanks in advance for any info.

I should add the Soil tester was around 5.5-5.8 when I watered with 7.0 water as per the instructions I read online(probably this forum).


I have purchased pelleted "Garden Lime" and I have it crushed up waiting to mix with some warm water until right before I water next (probably another 4 days or so since I just flushed it really well with the last solution).

Any help between now and my next watering session is much appreciated, else I'm just going in kamikaze(watering with the ex-pelleted lime solution) and hope I don't ruin my beautiful budding baby girls.

gotdank said:

I have purchased pelleted "Garden Lime" and I have it crushed up waiting to mix with some warm water until right before I water next (probably another 4 days or so since I just flushed it really well with the last solution).

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I had the exact same problem and the only suggestion I would make is, don't add the lime to the water. Instead just sprinkle the lime on the soil surface and water in with room temp 7.0. Use about 1 tablespoon of lime per 1 gallon of soil. It doesn't have to be exact though. You aren't gonna kill 'em with lime. Try to work it into the soil a little if possible without disturbing the roots. I just put it straight on the surface. Brought my ph from a 5.2 to 6.6 in a few days. I might add too that I wouldn't use that aquarium ph adjuster for your plants. That's what I used to begin with too and someone (on RIU I think) told me that it's not good for plants. I don't even ph adjust my water at all anymore. I used to spend a lot of time chasing that 'magic' 6.5 and all it ever did was piss me off. Our tap is a pretty consistent 7.2 so I just let it sit for 24hrs and go with it. In my limited experience, soil ph seems to have a tendency to lower over time if anything so watering with anything between 7.0-7.4 should help stabalize it. I probably wouldn't feel safe going higher than 7.4 though. Don't wanna invite problems. If you have to lower it or it just makes you feel better, try lemon juice. Good luck man..I hope everything works out for ya. Made all the difference in the world for my girls.

Thanks for the info man, really relieved to hear your story and know there is hope.

I did try initially watering with the lime 1 tsp per gal of soil by sprinkling it on the top, then the next watering I mixed it in with the water because my run off PH was low still. Hope fully this powder I have from grinding the pelleted lime will do a better job, Id like to see the plants get back on track like I had them when I was vegging.

My tap water comes out really high like 7.8, should I even try to lower it to 7ish with the aquarium PH Down?

again thanks for the knowledge.

No problem man. I'm a newbie to growing so I'm always happy to pass on anything I've learned through my own mistakes.
Yeah, forgot to mention that it actually took 2 applications of lime before mine got on track. Sorry about that. Maybe
water it again in a day or two and see it it has raised any. Mine were autos in little 1gal pots so it only took a couple of
days. If yours are in something like a 5gal, it might take a little longer to work it's way through the soil.
If I'm not mistaken (and I may be) unless you go WAY overboard with lime it'll only stabilize the soil @ 7.0 so if you add a little
more than you meant to, you're still good.

I'd definately get your ph below 7.8. If the aquarium stuff is all you got, I'd probably go with it.
Let me know what ends up working for you. I know it's frustrating shit, but you'll get it right with a little tweaking.

I had these types of run pH problems until I started using nothing but RO water. Now I have an RO system and have had no problems since. Only problem with RO is that you have to supplement with epsoms. Good Luck!

Divitus said:

I had these types of run pH problems until I started using nothing but RO water. Now I have an RO system and have had no problems since. Only problem with RO is that you have to supplement with epsoms. Good Luck!

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Thanks, I have a 3 stage faucet filter, but the funky faucet here isnt compatible, Im gonna get a new faucet maybe this weekend and start using the water from that.

I have a good amount of epsom salt, when my deficiencies first started showing I thought it was only mag deficient because only slightly yellow leaves were visible. no such luck obviously.

Ill check out the ladies PH in the next few days and apply the pelleted garden lime to the top of the soil and hope for the best.

Added some pics so you guys can see what I'm workin with,

Still waiting for watering day to re-test my soil PH. anxious as hell.

Took some clones, just so I can be ready for round 2. 6 in mini DWC and an extra I just couldn't throw out so I grabbed a rockwool cube and soaked it over night, just dropped it in.

Ok. I watered again today, I first did a little 7.0 water to test the soils ph on each plant and one was 6, the other 6.2. Great news so far, hope I can get it back into shape.

I added a teaspoon to each container, spread across the soil evenly then I mixed it in with the top layer of dirt with a plastic spoon. Then I watered as I normally would.

I'll keep updating as it progresses.

gotdank said:

Ok. I watered again today, I first did a little 7.0 water to test the soils ph on each plant and one was 6, the other 6.2. Great news so far, hope I can get it back into shape.

I added a teaspoon to each container, spread across the soil evenly then I mixed it in with the top layer of dirt with a plastic spoon. Then I watered as I normally would.

I'll keep updating as it progresses.

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Nice..glad to hear your situation is improving. You should be back on track soon. Keep us posted.

Not really looking too much better, I got some clones rooted so once these finish I'll get going on the next set.