Yes the PH will stabilize itself to about 6.0 area, give or take a few degrees.

For a medium I use rockwool for cuttings (clones), but also I use a small clone machine, then I either do DWC or a top feed, but also Canna Coco for a soilless medium in another room.

Yeah with Aqua it says that if you set the PH before you put it in the tank you can leave it and it will be ok, where as with Hydro you have to check and reset the PH once it had been in the tank for a while as usual.
I spoke the a man at canna and he said and i do quote " i would not advice the use of Aqua in hard water areas as the PH will be difficult to balance and to much acid will be added over time, Hydro ( hard) has been specifically designed for hard water areas and may well be the better choice" i totally agree, after using them both Hydro is for me obviously its going to differ area to area...

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I need to add ph down every day, with the canna coco. Maybe I should switch to canna hydro

yeah mate might be worth a go cause adding ph down everyday aint good as im sure you know, with the hydro i set it whack it in the tank , leave it over night then adjust in the morning i check it of course throughout the week but dont have to adjust it again..

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I actually was not aware of a problem with adding too much ph down. Does it lead to the buildup of salts?

It would be so nice not to have to muck with the PH

here mate read this really interesting chapter 8

http://http://www.hydroponicist.com/...1-water-ph.htm

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check your water at the tap PH. You may have a problem there with a high ph level. Usually city water is about 7.0. I have lived out in the country and seen the well water reach ph as high as 8.0.
I use coco currently and stick to the recomended dose of coco a and b and never have any problems.

Think u missed the point there mate..

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thanks for the link. I guess it should have been http://www.hydroponicist.com/pages/p81-water-ph.htm

My tap water is ph 8. After mixing with nutes its at about 7. PH down to 5.5 and every day it is at 6.2 or 6.4 and I knock it down again.

I got your page, it seems to recommend topping off? One time I got lazy and did not empty my reservoir and just refilled it. The PH did seem a bit more stable. Others have told me not to do that. Maybe I did not get your point.

sorry the link didnt work, we got there in the end..

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