Why is my PH always rising?

Hi i was wondering why my ph keeps rising. I mix up a full tank to (20L) to 5.6 and by the end of the day its up to 6.1. I have been taking it down with some PH down but i understand its not good to add too much or you will poison your plants. Also i hae noticed my leafes are drooping a bit towards the end of the day. The plants are in clay pebbles in ebb n flow system. Neuts and all that are spot on. It looks like over watering but i only flood the table ebery 6 hours. However the plants are still only about 8" so is this too much?

peace peeps

im having the same problem, my water seems to rise about.4 every 8 hours on average.

Are you guy's using rockwook with your grow rocks? What nutrients are you using and what are you using for Ph up & down?

i was just testing it via a bucket, nuthin added but water :)

Ah...then it will change. That's why nutrients have buffers, and good Ph up and Down is needed.

ahhh rite, i have ph down, need some ph up tho. 1 question zandor m8, my nutrient is canna aqua vega. is that ok to add to the water i use for my soiled plants?. also my rockwool seed has sprouted, shud i use fert on it straightaway? thanks again m8

Wait until the first set of true leafs are fully formed then start with ¼ strength nutrients. I have people using GH 3 part for hydro and soil growing so I donâ??t know why yours would not be the same. If you are going to grow in rock wool and then into soil wait till you have the 3 set of true leafs before you transplant it. That way you can split the rock wool and remove as much of it as you can with out hurting the roots or plant. That crap will hurt you later by holding more water closer to the root ball then the soil will. Just something to think about.

Hey i use canna a-b nuets for hard water (im in london with hard water) with canna ph down. I have 1" rockwool cubes supporting my plants in 3litre pots filled with clay pebbles in the E&F table. I usally dont flood my table deep enough to get the rockwool cubes wet but i didnt know it was a problem if u did, but i can see what your saying. But still i add my nuets and they do bring the ph down but i still have to use a little ph down to get it right but then it just keeps rising. im only running like 650 ppm though including the down when i up my neuts will this help stabalise my ph?

Yes, more nutrients is also more buffer. So if you are starting with hard water (what's the PPM of the hard water?) I would guess as much as 350 PPM or better. You Ph ballance the water then add the nutrients mix and wait about 10 min check again and then re-ballance the Ph if you need to.

Should this water be heated at all?... and to what temp?

The safe range is 60-75f for the reservoir. Nutrient solutions at a temperature of 62-68f will hold much more oxygen then 75f will.