Magnesium deficiency?

Just noticed a couple of spots showing up on the top leaves of one of my plants. Been feeding General Hydroponics Flora series. About 5 days ago, I switched from liquid koolbloom to dry koolbloom. Not sure if that's related. I checked the pH of my soil today and it's right about 7.0 (maybe just slightly above). It's tap water from a well. Maybe a little hard, but I do have a water softener installed.

Am I right about the Mg deficiency or could it be something else? Treatment options?

Your water softener is a real problem and you may need to flush before it catches up with you. Check the ppm of your run off, probably higher than what you are feeding with, or will be shortly.

What happens is the water softener system swaps out your mineral content for dissolved salt. The salt will build up in your root zone until it reaches critical mass (toxic salt build up). This will absolutely fry your plants when it happens, sucking the moisture right out of them.

You'll want to look at adding a Reverse Osmosis (RO) system to your water source to get rid of the salt content.

I'm not sure this is related to your spotting, just something you should be aware of...because it is coming.

Good call on the water softener. Didn't consider the implications of that. They've been real healthy up until now and I'm in the home stretch. Maybe 3-4 weeks left. I was thinking of just 1 more feeding for them, or more likely cutting the top earlier and giving the rest of the flowers another week or so to mature.

Worth using FloraKleen in the next watering? It's supposed to help dissolve accumulated fertilizer salts. Is it too early for a final flush?

i would say keep doing whatever you are doing maybe add some micronutes( i know that AH has then for hard and soft water) ; pH your water to 6,5 if possible

I would absolutely run a cleaning agent through them on next water. Softened water doesn't bite you in the ass until about the 3 month mark which truly sucks because when it bites, it happens very fast and it is very devastating. Lost a crop near mid-flower by not understanding this!

You're right...I was just researching water softeners. From what I understand they strip out calcium and magnesium and leave a trace of sodium in water. For the rest of the grow, I will probably just get a few gallons of distilled water and use that. In the mean time, adjust the feeding schedule or maybe just the distilled water + micro nutrients until the final flush?

beaz,
Another water option...there must be some way to draw water from upstream of the water softener, at the water softener inlet line for example. Test that for ppm and then use un-softened water if it's under 250 ppm.
JD

Thanks for all the feedback guys. I think there's certainly some lock-out going on, but also sounds like it's too early for a final flush.

My plan is to get some distilled water and maybe add some pH reducer to it for the next watering. If the soil pH is 7-7.5 now, the runoff is probably higher. It makes sense to try and clean some of the salts out of there. What should I adjust the pH to in the water...would something around 6.0 make enough difference without shocking the plants, or do I go lower (5-5.5)?

Also, should I add some cal/mag supplements to the water?

My humble opinion...

Just give them a decent flush wit tap (or distilled) water to clear as much sodium as you can, then give a half strength feeding. The pH of distilled water is meaningless because it has ZERO buffering ability. Adding even a drop of pH down will drastically lower the pH of distilled water, but that DOES NOT mean that pouring that low pH water on your soil will have any affect on your soil pH.

In simple terms.... Water (even loaded with fertilizer) is a relatively weak buffer. Soil is relatively strongly buffered. In a pH "tug-of-war" between your soil and the liquids you pour over it, soil wins every time. If you want to address the pH of your soil, do it when you mix up the soil in the first place. Or study up on organic methods in which the pH is largely managed by the living soil microorganisms.