Having trouble correcting PH!!!

I'm almost 40 days into vegg and growing in 60%coco and 40%perlite in 3gal pots. I've had no problems with my feeding schedule of feed,feed,flush. But just last sat when I flushed with 3gal/each pot 900ppm pHed to 5.8. All plants run-off jumped up to 6.5. I didn't try to re-flush but waited until Monday where I fed normally with 1.5gal/each pot of 1000ppm pHed to 5.8 and run-off was around 6.3. I let them wick majority of their water before trying to flush again. I was told to flush with 300ppm water pHed to 5.0. I only had enough water to flush one of my plants and even after flushing with 5.0ph water the run-off was 6.5! Do I keep flushing with 5.0 water til it reaches 5.8?

Might check the coco growers thread. I was thinking add a tsp of dolomite lime. to help balance your Ph. I added a tsp per gallon of coco blend to my grow. Ph'ed my water to 5.5-7 and called it good.

Flushing with such a high ppm is where I went wrong right? This is only my 2nd time growing in coco. I know that I'm to never flush with just plain water. But it was never clear what I was to flush with. So I assumed that I should flush with just base nutrients and no additives. Just as long as I flush with alot of water. Never had a problem til now.

Just water... forget adding anything to it bar balancing Ph.

Plain RO water? So don't add anything at all? Wouldn't that ruin the coco?

no the coco doesn't have anything to ruin. the point of the flush is to remove all the salts and nute build up. After flush go back to feeding. I only flushed twice using the blend. Probably would have been good with once.

oh ok thanx alot. ill go ahead n try it n see what happens

i totally agree flush (r/o or even better distilled water)