Noob having problems... Any suggestions?

First post here and first attempt at growing

RDWC - 32 gal total in two totes - one plant - 700 gph pump (yes, massively overbuilt
Chiller - water temp stays between 60 - 68 degrees F
600 watt MH that is about 4 inches from plant
temp at top of plant ranges between 70 - 80 degrees F

Started from seed in rapid rooter plug
the small plant photo is 2 weeks ago
large photo taken this morning

Earlier I thought the browning of the leaves was nute burn, so I tried reducing the levels - no change

Recently I have decided the issue is low pH resulting in calcium deficiency - so yesterday I changed out all water and replenished all nutes. Currently about 750 ppm and 6.0 - 6.1 pH

Questions: Should I remove the burned leaves? The ones that are somewhat shaded look fine, but it seems the ones that are exposed to the light are the ones affected. Any other ideas regarding cause and remedy?

Thanks...

1.) 4 inches is way too close for a 600w MH.

2.) 750ppm is way too much feed

3.) dont use ppm as a term of measurement unless you know what scale your meter uses and can list that as well. better yet use EC

4.) keep ph between 5.6-6.1

first, thanks for the helpful suggestions.

I immediately raised the light to 12"
I'll need some time to filter some more RO water to address #2 - using this schedule...
My meter only measures ppm, I will check out using an EC meter
The 6.0 - 6.1 pH is my target, assuming accurate metering.

Again, thanks! I am hoping to keep this plant alive long enough to complete the cycle. Wish me luck.

Using the attached schedules...

Or just figure out what scale it uses. I wouldn't go out and buy an EC meter. But when that one dies i'd look into it.

Target PH should be 5.8

Move the light 18 inches for now while plant recovers. 12" is the closest you wanna be.

Got it.

Done.

Thanks again!

ohhh dear..

carry on .

This picture makes me sadder than the commercials with starving animals that need your help now!

Do not cut anything let it grow out and do what everyone said to do

I'd put that light 3 feet away until it recovers and stretches out alittle, for me 18 inches is about the closest I get when strong and healthy.

The top of the plant isnt even burnt. Thats more nute burn than light burn imo.

firsttimeARE said:

Or just figure out what scale it uses. I wouldn't go out and buy an EC meter. But when that one dies i'd look into it.

Target PH should be 5.8

Move the light 18 inches for now while plant recovers. 12" is the closest you wanna be.

Click to expand...

Could you explain that to me please? Maybe it will help this grower and others as well..

I just bought an HM PPM pen. My tap water reads 540 ish and my RO water reads .004. The package states that the pen is calibrated using an NACL 342 solution...

I think most hannas use .5 conversion factor. That would make your tap 1.08EC. Which is some awful tap water.

firsttimeARE said:

I think most hannas use .5 conversion factor. That would make your tap 1.08EC. Which is some awful tap water.

Click to expand...

I concur... very awful tap water. I have well water that reads 540 and its nothing but lockout central when it comes to nutes.