some people also claim, the longer you go without switching out your nutrients batch, the more build up of the different kinds of nutrients there will be in the reservoir. I am currently doing a trial run with a single plant and using 5+ years old nutrients. I started out with clean water the first two days and then EC 1.2 on the 2nd day, then after 8 days I mixed a new batch with EC 1.72 (people suggest EC 1.4 I think, but I studied my nutrients schedule sheet from their website, and they suggested 1.7). This batch I got going for 13 days now and she is looking great, the EC is currently at 1.3 and i'll keep this batch going for awhile still. All this time I keep an eye on the PH and I add more water to the reservoir as it lowers in the tank. I use regular tapwater that's been out over night, I keep the PH at 5,8. These last couple of days PH been going down a lot, I try not to let it go down more then 0.5 before adding more water to get my 5.8. It is said that if you let your PH go up and down too much, and you have to raise and lower the PH with 1 or more levels at one time, it will shock the plant.
Damn I am stoned right now, where was I ? hehe, well maybe i will make a real journal of my current grow some day
edit: because of the so-called build up, only add clean water and no nutrients, only add nutrients when mixing a new batch for reservoir. That's what I'v learned at least.
2nd edit: The first couple of days with clean water, I make sure that the water level inside the reservoir is very high so it's got the rockwool cube submerged and airstones beneath.
