HELP! with hydro ebb and flow under 2 UFO LED

Hello,

This is my first post on RIU. My setup is a closet grow using a Growlab 80 with a botanicare Ebb and Flow 2' square tray with 2 90W UFO LED lights. I've got 24 pots with hydroton with various strains such as GDP, Purple Kush, Cheese, Purpetrator, and Shiva Skunk. I've got a tri-meter measuring water temp (75-70 degrees), PPM=500, pH=6-6.5. I have the plants on 18/6 light schedule. The plants flood 5 times a day for 15 minutes while the lights are on. I'm using the GH FloraGro, and FloraMicro with the recommended mixture. I've got a 4" exhaust fan going out of the growlab. I don't have an intake fan, but the growlab isn't airtight by any means so it brings in fresh air. Don't mind the 10 small clones in the front...most of them are cheese clones that took forever to start rooting and are now starting to have some new growth in a bubbler. All of the plants in the growlab have some yellowing lower leaves and yellowing tips. I know that some of the yellowing was caused by heat and the lights, but I've moved the lights to 2 feet above the plants and the heat is down since I installed the exhaust fan. Please advise me on what to do! I've attached a few pics with the lights off of two of the GDP plants that have taken a downturn. Please advise me on what I should do. I'm thinking about doing a res flush and adding some epsom salt. Please let me know if this is ok. Any advice is appreciated. I can take more pics if there is interest. I easily have over a grand into this setup and I just want to grow some good herb.

When you say the "recommended mixture" in regard to your nutes, do you mean what's printed on the bottle?. Full strength is way too hot. The ppm at 500 seems a bit high for those young guys, so I can only guess thats the case. Additionally, the ph is way too high at 6-6.5 for your setup, which can promote the growth of pythium/fusarium (root rot) and that is not a good thing. Try and shoot for the 5.3-5.8 neighborhood.
How well, if at all, is the nutrient solution being oxygenated before it's flooding the table?. I only ask because a few look overwatered even though your cycle doesn't seem to be excessive.. Perhaps a pump and air stone purchase is in order.

BurntFinger said:

When you say the "recommended mixture" in regard to your nutes, do you mean what's printed on the bottle?. Full strength is way too hot. The ppm at 500 seems a bit high for those young guys, so I can only guess thats the case. Additionally, the ph is way too high at 6-6.5 for your setup, which can promote the growth of pythium/fusarium (root rot) and that is not a good thing. Try and shoot for the 5.3-5.8 neighborhood.
How well, if at all, is the nutrient solution being oxygenated before it's flooding the table?. I only ask because a few look overwatered even though your cycle doesn't seem to be excessive.. Perhaps a pump and air stone purchase is in order.

Click to expand...

I forgot to mention that I have a dual outlet air pump with 2 air stonesin the reservoir. I'll flush the res today and add a lower nute mix and see how the next couple days go. Also I'll try to keep The ph down to 5.5-6.

Sounds like a plan...
Typically General Hydro 3-part can and will illustrate any certain strain's fickle little whore syndrome(copyright), for their much needed intake of micro nutrients because of a wavering ph level. For obvious reasons, I usually found it to be more of a problem with DWC than anything with roots that are constantly sitting in and suspended above a nutrient solution. However, with a multi-strain hydro setup or any setup for that matter, it's about finding that equilibrium of light/temperature/ humidity/ph and ppm levels so that every plant is happy.
I suppose I should ask if you know what the temperature of your reservoir is and/or if there might be a light leak in it?. You wouldn't want to be introducing bacteria into your nutes before they even flood the table. Also, makes sure you're frequently checking those stones for clogs as ones with a lot of buildup tend to put unnecessary stress on your pump, stones are cheap...pumps are not. Lastly, I'm not too familiar with using LED's for cultivation so 2 feet seems awful far away but, if it's too hot for the back of your hand than it's too hot for your ladies. Just use your best judgment.
Hydro can be a difficult way to grow if you let it overwhelm you, but with a little patience and effort you should be well on you way to smoking some Kind nuggets. Word.
Good luck and happy gardening.

I have not read everyone ones response, but a few things caught my eye. U mentioned heat stress, if i am not mistaken.. Really??????????? Under two 90 Watt UFO LED?? Just set up an oscillating fan, i guess... And i would try dropping your pH to 6.0 and let it either drift to 6.2 (no higher) and no lower than 5.8.. Watch your temp on water.. U already nailed one very important thing-u keep your nuts fairly weak and thats good because u are in hydro and under LEDs..
Maybe everything is fine and u need to change your solution more often,... Just trying to brain storm and maybe sow a few thoughts.. Good luck..