I put in 1/4 strength nutes.

I have a pH testing kit, what's an ec kit? What should I cover the rockwool with?
Thanks for the advice.

I never known what percentage wise i put in as i just pour the bottle give the solution a stir and then put the meter in to check the ec, if its too high add more water if its too low and more nutes. I never go off the bottle instructions.

An ec meter is a meter that measure the Electrical Conductivity of the water, because you are adding minerals into the water this raises the ec, so when its at the right level you definately got enough nutes in there.

Dont confuse this with another scale though which measure in ppm, from what i know ppm is reached by multiplying the ec level by 500 or 700, because of this variable this makes the ppm scale less accurate as people use the different figures.

some ec meters
eBay - ec meter, Gardening Plants, Pet Supplies items on eBay.com
i got a nutra wand which gives multiple scales so you can see it in all the different ways.

the reason for covering the rockwool is if the rockwool is wet with nutrient fluid and recieves light this will create algae which will suck the available air from the rockwool.

I got some of those black bin liners and coated the top of my rockwool cubes

Thanks, great stuff nongreenthumb. Would tin foil be ok to cover the cubes in?

you could use tin foil, but if it creases it will reflect the light back unevenly on the plant plus also wouldnt it be effectively like cooking the roots slowly, just as long as light doesnt hit the rockwool you will be ok you could even do it just by covering them with the hydroton

yeah good job mate!

__________________
So if you're a fighter
and scrappin' a lot,
You'd best shy away
if you're scrappin' a Scot.
Wi' one fuckin' blow
yer head will be squished,
Then he'll let his scottie dog
lick the blood from his fist...

but he meant that in a nice way man!!

I'm always curious. This 2x4 frame that holds the 40 gallon resevoir. Does that frame sit on the floor of the tent?

Sorry brain fart. Just getting caught up. Welcome to the forum. I just looked at one of those setups yesterday and wondered if anyone would adjust them for hydro or aero. Your are using flood and drain? I'm just trying to get an idea af how tall this is getting? 12 plants, 40 gallon res? The water your are using, tap water? And non is right on you need an EC meter. You have invested some time and money in this setup. It would be a shame if you didn't get maximum information to achieve maximum results. If I am picturing this set up right, and right now thats a big if, you will want to do an EC on your water before adding nutes, and adjust for it i.e. E.C= .3, target Ec 1.8, Ec with nutes= 2.0. I apoligize for the rambling. Part of our job is to test the harvest. Stoned again.

The 40 gallon res. sits on the ground, under the 2x4 frame supporting the tray. All this is inside the tent which is basically a skin hung on a steel frame.

Yes, I'm using flood and drain. The bottom of the tray is about 1.5 - 2 feet off the ground. There is about 14 inches of slack on the light (hanging from the roof), and the entire tent is only 6.5 feet tall. This means I'm only going to be able to have the plants get about 3 - 3.5 feet tall.

I'm using tap water, but pHing it and then adding the nutes. I'll have to get an EC meter.

How often should I water? I've been watering every four hours for the first week, but then I read that's too much so I've only watered them twice in the past 24 hours -- with just pHed tap water because I wanted to flush out all the nutes.

Ok, so I had to move my grow spot to a different location, too many people were finding out. But now, it's too cold in the new spot. I have the lights on at night so as not use peak hours and the fans are always running to supply the plants with new air. I checked the thermometer this morning, last night's max temp. was 71.6 degrees, min was 61.3 degrees. I have them under a 1000w MH lamp, about 18" above the plants. How can I get more heat without sacrificing ventilation?