Phosphorus? To much Cal/Mag. Can Anyone please Identify?

These plants are almost 2 months old now and this has been going on for about 2 weeks. I just cannot seem to find a solution. I have been using cal/mag for over a month, just ½ tsp per gallon. The stems of leaves and some stalk on one of the plants are turning purple, so I assumed it was a phosphorus deficiency. I started supplementing with Fox Farm Organic Liquid Food, (0 - 0.5 - 0.7), 2 tsp. per gallon. This did not seem to help. I was using Ph water at around 6.2 – 6.5. and when I checked the runoff it was at 5.8, so I increased my water Ph to 6.8-6.9. I switch to Bat guano thinking maybe it could be a nitrogen problem, plus the bat guano does have some phosphorus in it. Still getting worse. The leaves are thin, still have purple, you can see in the pictures what is happening to the leaves. Just hoping someone has delt with this before and can shed a little light on this for me. Thanks

• Strain: Mowie Wowie, ILGM, 6 plants
• Method: Soil, Happy Frog
• Vessels: Pots
• PH of Water was 6.2 now 6.8
• PPM/TDS or EC of the nutrient solution if applicable, was using cal/mag but stopped because wasn’t helping. Tried fox farms organic food because though it was a phosphorus problem because of the purple color. Switched to bat Guano thinking could be nitro def.
• Indoor Tent Grow 8x4
• Light system, LED 2x 1500W LED Grow Light with Bloom and Veg Switch and 2x Mars Hydro TS 1000W Led Grow Light
• Temps; 75 Degrees
• Humidity; 45
• Ventilation system; Yes, 8”
• No - AC, Humidifier, yes De-humidifier outside of tent
• Co2; yes 1100ppm

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Tag an experienced grower,put an@ in front of their nameLet’s try @kellydans

When I saw 1,100 ppm of CO2 that tells me you are in a very different category. This could be any number of issues: if light is under a certain PPFD it’s nute burn. If your PPFD is adequate for high partial pressures of CO2 then could easily be nute deficiency. Do you have an idea of the amount of light produced?

How big is the grow space, how many watts from the wall are you drawing?

I suspect based on the information provided that your plants aren’t seeing much of that CO2:

This would be helpful to help diagnose your problem:


Sorry it took so long to get back to you, I had to order a TDS Meter. So my grow space is a 4x8 tent and my lights are drawing a total of 1010 watts. I’ve stopped the co2 for now, because I really didn’t know if it was helping or hurting. The ventilation I had turn to low and my meter was at plant level so pretty sure they were seeing the co2. So I checked the ph in the soil and it was at 6.6. The TDS is at 235 now. I did give them some molasses yesterday, and removed about 50 leaves that looked damaged. They look a little better today, not as pale. I know the TDS is low, but not sure what that means. Thanks

TDS meters have a little X10 symbol on the display. I suspect your TDS is 10 times what you reported.

I don’t see a x10

I have the same meter it’s not a x10 to me it looks like a cal mag issue but doesn’t make sense if you are adding cal mag and a ph of 6.6 is good for uptake of calcium and does take up to two weeks to show a difference in soil I would check calibration Of ph. Meter

If you wouldn’t mind verifying the runoff TDS in PPM (500 scale) before providing a fix I’d feel better.

I would expect to see over 2K on the meter using soil. If it’s that low you will obviously need to supplement. Let’s make sure before you do.

No problem, I’ll be watering them later today, I’ll check the runoff tds and ph. Thanks

Ph meter is brand new and seems to be working fine. It’s always been 1/4 top to bring my water to aph of 6.5. My old meter quite working and I just got this one a week ago

Cool sounds like everything is covered my friend410 is on the correct path I am a ff soil grower and start nutes when ppm fall below 800 which is conservative compared to others here but you’re in. Good hands happy growing :potted_plant:

Okay I got the runoff numbers. The ph is 5.88 and tds is 2048.

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That’s more like it.

If it were my plant I’d likely flush to around 1,200 ppm then supplement. Including cal mag. Input TDS should be around 1,100 ppm.

So what if flushing is not an option, I’m scrogging and the plants are all intertwined in the netting, all I’ve got under the plants is a small plastic catch. Is there any other way to get the trailer lowered or any other option

And this is why I always recommend one screen per plant.

No idea what to tell you. Put a bigger tray under plants and flush all of them. Use a turkey baster or hand pump to remove excess.

Okay thanks, didn’t know if maybe running hydrogen peroxide mix would maybe do the same. I’ll do what I can. Thanks

So you say flush to 1200, does that mean I’m not pushing 10 gallons through, ( 5 gallon pots). Just flush until I get it to 1200? Also I have another quick question. When I water my plants, should I be watering until I get runoff each time. I’ve just been given them one watering can full, 54oz a day and really don’t get any runoff. Thanks again for all your help.

It may take more, or may take less. But that’s how I would suggest doing it. Then you KNOW.

Always water to runoff once plant is big enough to use the space in the pot.

So all flushed they are all between 600 - 900 ppm. So do I let them dry out some before watering with cal mag and nutrients, and still 1100 with them being a low as they are. Sorry so many questions I’ve never flushed before so just not sure. Thanks