PH mistake and PPM question

I recently switched to flower 12 days ago and up to then I had been mixing water by the gallon. I was tired of mixing 1 gallon at a time and bought a spigot for a 5 gallon bucket so I could add Cal/Mag, mammoth P, and PH down for my flowering plants. After the 3rd or 4th water I noticed some yellowing of the leaves and recognized it was PH because it happened before. My mistake was that PH’d the water first for some crazy reason and just realized I have been giving my FFOF plants 7.1 PH.

I am on untreated well water and my PH is 7.5 and PPM is 190 with no treatment.

My 2 questions are,

Should I flush them with the proper PH water or just wait until tomorrow when I water again?

After I add the recommended amount of Cal/Mag my PPM is 420, is that too low for soil and should I add more Cal/Mag or something else?


I always follow the recommended amount. I think mine is 1 tsp to a gallon. And my ppms in, is about that. I only calmag on just water days. I have been reading on how some nutes can kinda lock out calmag if given at a feeding. Try watering with a lower ph. If ur run off is 7.1 i would try like 5.5 to 5.8 next water and see if that lowers it some. Or you could always flush and start over.

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So I wanted to give a little more information since this is my first grow and I’ve read some other post.

My plants are 12 days into flower and they are Harlequin and ACDC from Medicine Man Seeds in FFOF with a top dressing of Down to Earth All purpose and Mykos. The only nutrients I have used thus far is Cal/mag and Mammoth P. I have a sealed grow room with a mini split, dehumidifier, and an Autopilot CO2 regulator/monitor.

I just tested 2 plants after accidently watering with 7.1 water for a week. Here are the results and a picture. The 2 Harlequin are fine since I caught it, the clone and the big ACDC in the circle are the 2 I tested.

Well water used today with Cal/mag and Mammoth P with a PH of 6.4 and a PPM of 468

Runoff from plant 1 (clone taken for sex) that is 5 weeks into flower was 6.8 PH and 1148 PPM
Runoff water on plant 2, 12 days in flower was 6.5 and a PPM of 866.


How long did you veg for in that ocean forest? Your runoff ppm is suggesting they’re not eating OR you still had plenty of nutrients in the ocean forest and they didn’t need extra nutrients yet.

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They were in Veg for 12 weeks because I was waiting for my clones to show their sex. At week 4 of flower on the clones I was confident that I had all girls (I have another post about that) so I was headed to the flower room with them from a tent and looked down and was like oh crap, I had 3 males. I forgot to add the Down to earth and Mykos until week 11, so I only used 1/2 the amount 3 weeks ago.

Yeah, that’s more than enough time to deplete OF soil nutes so it’s not that. The plants don’t look bad at all from the pic you posted. Your ph looks corrected from the last runoff. Next time they dry out water them and check the runoff again and see how much the ppm has gone down. I don’t see a ton of pistils so they’re likely still in transition and the newer growth is yellow a lot of times during the stretch

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Transition to flower will make the plant look very pale from all of the new growth FYI.

Plants look good but your soil looks like it’s fairly depleted. What size pots are you in as that can cause issues with an over-developed canopy in small pots (like a 5 gallon) and inevitably will cause issues later.

What lighting are you running? CO2 is likely only of benefit if you are at a very high light value (PPFD-photosynthetic photon flux density) so the plant can accelerate it’s growth.

If it were my plants I would be supporting it with some vegging nutes along with a dose of P and K along with your cal mag (although less necessary in soil). High intensity lights do require cal mag in general.

FF recommends flushing at regular intervals to remove waste salts—has this been done?

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The plants are in 3 gallon pots, guess I made a mistake on that one. All the plants look awesome except the yellow on the biggest one.and 3 of the 4 do have pistols all over them which is funny since it took the clones a month. The biggest one is the only one that doesn’t have much yet.

My lights are Spider Farmer SF 4000 which is very similar to a HLG quantum board light but 1/2 the price.

No I haven’t flushed. I was trying to go with as little nutes as possible because I am making this all into RSO, so I didn’t even pay attention to feeding schedules until I was researching this today. I am definitely an amateur, but I am learning everyday thanks to this website.

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You have an excellent start and I’ve seen experienced growers do less. You need a small tuneup and we will all have to stay out of your way after that haha.

You’ve got some really killer growers here. I might suggest if you haven’t to look into the ‘edibles’ thread and acquaint yourself with @blackthumbbetty for anything edibles.

You can run nutes and still end up with a clean product using a flush technique at the end of the grow.

Oh, feed your plants.

A proper flush before harvest will clean them right up. I love RSO/FECO!

Thank you for the input and for the hookup. I will definitely be looking for advice on edibles.

So I have one more question. Since I’m using Fox Farm, should I use their nutes? My wife has Advance Nutrients Micro, Grow, Bloom, Voodoo Juice, Big Bud, B-52, Overdrive, and Rhino Skin, but I can get something else if its better for my soil.

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If you have a handle on the different products there is no reason you can’t use them. I would go to their website and see what grow schedules are published and use one of theirs with the only caveat being to keep your TDS at reasonable levels. Some grow schedules are wildly optimistic about their nutrient line which makes sense as they aren’t in the business of conserving nutes haha.

I use GH and have used it in FF soil just fine.