leaves turning light green to yellow

hi all i hope you can help i have 6 plants, since day 1 4 of the plants have a few leaves turning lighter and lighter green with dark green veins some leaves have a burned tip and edge, the leaves are straight except very tips bend down they are 2 weeks into 12/12








E-indoor or outdoor - indoor 5x9x8 sealed, 6in exhaust fan, 2-4in fresh air openings
E-soil, soilless, coco, aero, or hydro - hydro
E-specific medium - hydroton
CSL-Soil type/brand
HCL-Hydro/aero/soilless system type -6 5 gal buckets recirculating dwc drip fed 30 gal res
SCL-Anything you have added to the soil
SCLR-Soil or slab runoff pH
E-Water source-city tap water
E-Source water pH-7.0
HRT-Source water EC (if hydro)-31ppm
E-Age of plant- 2 weeks since 12/12
E-Type of fertilizer- gh 3 part 5,10,15 mmpg, koolbloom 7mmpg
E-Rate of application (if hydro, this is your PPM number, preferably after each component is added) - 1000 ppm 5,10,15 mmpg 30 gal tank
E-Lighting source and distance from plant- 1000 watt hps bulb in a sealed air cooled reflector powered by a 1000 watt switchable mh/hps remote ballast, 18-24 inches from plant
E-Air temperature (both day and night if you are running a dark period)- 80 degrees f.
HD-Reservoir temperature - 76
E-Air % Relative humidity- 65
E-Lighting schedule 12/12 7am-7pm
E-Type of ventilation your room - 6in exhaust fan, 2-4in fresh air openings 2 wall mounted recirculating fans
TR-Did you pre-soak your media in pH corrected solution? - presoaked 24hrs

Your res temp is pretty high. What do the roots look like? Brown? Slimy? My guess is your roots are rotting. Either get more air in there or get a CoolWorks IceProbe and chill your res.

PH a little on the high side also if you are not adjusting down from tap

One thing I don't get is why the troubleshooting form asks for the source pH but not the pH you are actually applying to the plant. Hopefully, mrnasty is lowering his pH to around 5.5. I think Stinky or whoever typed that up must have been :stoned: at the time of doing so

I like hydro ph from 5.6 to 6.2 ALWAYS.

what is minus 31 ec and how often do you calibrate your meters?

I think the hyphen is just separating the question from his answer and his tap water is 31 PPM.

hey thanks guys for your reponses. the roots are brown but not mushy. im working on getting the res temp down using ice blocks. my res ph 5.89 ppm 924 when i drain buckets back into reservoir ph 5.94 ppm 938. some older leaves have yellowed and the veins are dark green

Sounds like you have the beginnings of pythium (root rot). Ice blocks will work but it will dilute your solution as they melt, which could be good or bad. I've been using water frozen in 2 liter bottles to keep my temps down. Its sort of a hassle, and you have to swap them out every 4 hours or so and since they take like 12 hours to freeze, you'll probably need to have a rotation of about 3 or 4 of them. But your only other option is to get a Coolworks Ice Probe because the max temp your res can be is 75 or the roots will rot and your plants will continue to suffer.