mag deficency or salt build up?

Just noticed this on a few leaves and wanted to be sure on what the problem was before it gets out of hand. I am using FFOF soil and Osmocote Plus for nutes. I water with tap water, I have those paper ph strips that I tried and it looked like the tap water is around 7. The plant is 33 days into flowering, using 150w hps, in a 2x2x5 tent with temps around 77-80. Thanks for your help

id put my $ on salt build up lockin out mg

Should I just do a flush? I can see some salt build up on the bottom of my smart pot. Is there anything I can do besides flush?

Are you phing your water down to around 5.8 or so?

No... should I be doing that? I thought I should use ph neutral water?

I'd pH the water between 6.3-6.5...I like 6.5. 7 will cause lockout and if ur getting precipitate(salt) forming, ease up on the nutes a little. If u can see salt buildup, the suspended precipitates u can't see are much worse. Flushing isn't needed unless uve gone too far with the nutes. I'd suggest using water only for a bit at 6.5 then SLOWLY introduce a low dose of nutes. Don't feed every watering.

The salt buildup is getting more noticeable on the smart pot now... I think it may just be the tap water that I have been giving her. After flushing I noticed a bit more salt on the pot, I am not sure if that is because I flushed a bunch of the salt out of the soil and into the pot or if the tap water is just bad here. Now I am thinking I should flush again with some filtered water or something... I really would love some help with this. Would brita filtered water be ok? or should I go buy some water?

@ilovebush the problem is that I am using a controlled release fertilizer and can't stop feeding nutes... although it is supposed to be guaranteed to not burn your plants.


I pulled a leaf that looks worse than the first pictures to try to help you guys help me. If it is a mag def then I read that I should foliage feed with a mix of 1 tablespoon of epson salt to a gallon of water.

vash2126 said:

.....snip........
I pulled a leaf that looks worse than the first pictures to try to help you guys help me. If it is a mag def then I read that I should foliage feed with a mix of 1 tablespoon of epson salt to a gallon of water.

Click to expand...

Ok I'm just finishing my first indoor grow so what do I know, LOL but when my plants had those rusty, punctate, spots it was a Magnesium deficiency. I put 2 tsp of Epsom Salt per gallon in my NFT reservoir until I got some Cal/Mag liquid (already dissolved and easier to just measure and dump in the res). Best of luck on the rest of your grow.

Can I foliage feed with cal/mag the same way people are saying to foliage feed with epson salts?