Brown Spots

My hydro starts are getting a few brown spots towards the serrated edges on some of the older growth and the tips are slightly crispy. New growth looks very good. I'm using GH, and mixed according to the instructions. PPM was high so I diluted it and make sure it's always under 250ppm. pH is 6.7-6.8, BUT I can only check with a soil meter and pH paper. Both read under 7. I had some problems with water splashing my starts as it dripped, so I added more hydroton. I was donated three medium vegging plants from a friend who told me to spray when I add them to my room. I made up a 1% solution of Earthtone and sprayed lightly. Everything is under High Output Florescent light.

ok, hydro, you want 5.8 PH, not 6.7...your roots are not absorbing nutrients with PH that high in hydro...Also if you are in full swing 250ppm is REALLY low nutrient wise...give us pics for a better diagnosis

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I'm going to lower the pH, but I've heard to gradually do it? The plants are rooted clones under 6 inches. They rooted in tap water and were added maybe two weeks or so ago. I'll see if I can get a good pic.

yeah gradually, but not as in a month to do it, just a day or two, every couple of hours to lower it. get a pH pen...

These are the best pictures I could get with my phone...

Actually the pH is 6.3 and has been 6.3. I don't know what I smoked to remember 6.7. I added a little pH down. It says on the label just a few drops so that's all I added. I stirred up the water and I'll go check it in a few.

your PH needs to be 5.5... if your using RO water and your solution will automatically buffer to 5.5 with GH nutes. i am currently running LF, and just simply follow this guideline:

in high light intensity (per gallon)
8ml micro
16ml bloom

in low light intensity or veg
5ml micro
10ml bloom

Plants BEGIN to absorb Mag/Cal at 5.8 PH in Hydro. Setting your PH to 5.5 is a good base but you should definately let it slowly rise to 6.0, letting the plant feed on every nutrient it may need.

Ive got a 5.8-6.2 PH with 1.2 EC (Sensi A/B and Cal-Mag) with an Anti-Wilt foliar spray and I STILL cant stop some def I have. Leaf tips get deformed, go yellow/brown/wilt, redd-ish stems, I just cant diagnose it. I added more of the Sensi Part B today though (high in P-K, I think its 0-2-5?)

you're right about 5.5-6.0 or 6.2 being optimal range. You should flush your plants from time to time, when problems occur. If a plant is hungry in soil it is not because it's lacking food but rather because it is prevented from eating it.

What is the feeding regime times you are using in terms of the pump running.

Jonus said:

What is the feeding regime times you are using in terms of the pump running.

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The pump always runs or the plants will all dry out. It's hydroton not soil. I've only had them running for two weeks and changed the solution after the first week. I check ppm and top off with water.

Okay. Update. Over two days I lowered the pH to 5.9. I'll check it today to see if it actually went to 5.8 after it ran for a while. It probably went back up to 6 when it mixed with the water in the bottom of the other buckets. I have a few questions though...
How far should I let the pH drift up before I lower it again?
Should I flush (or are they deficient in something and a flush harm them)?
How long should I flush for if/when I do?

don't let it go above 6.0. best method is to lower to 5.5, then let it drift back to 6 and again 5.5, etc.

yeah flushing for like 12 hours should do them good I think, but I'm not sure how this works in hydro. Perhaps you don't really need to flush, as your plants are not in any medium (hydroton doesn't really count)

Likely you overfed it. Back off to low ppms. I'd like to see 300-400 an even low npk. No flush.

I start at 5.2 within 3-4 hours its at 6.0 right where i want it. I don't like lower than 5.8. 6.0-6.2 is best for my situation