Ph changing drastically..

I am on my first Aeroponic grow, and it has been going great, except in my third week of flowering my PH keeps dropping a lot - I have to raise it up 3-4 times a day to keep it in the 5.8-6 range. Any idea if this is normal? Can't find it mentioned in my books. If not normal, what would cause it?

When plants initially get the nutrient soup it contains a measured amount of minerals and other elements that are essential to the plants growth. Over the course of growing a plant may take x amounts of one mineral that is alkaloid and x amount of another which is basic. This can throw off your ph as well as your plants if you don't keep it in check. Some nute solutions with ph buffers prevent this from happening (as much). P.S. always top off with plain water!

thanks! thats what i was hoping..

i've noticed a dropping pH during vegetative and an increase in pH during flowering.

if you are decreasing in veg thats normal..nitrogen and phosphorous based food affects ph....if you are going up and down in bud thats normal too..but your plants could use a little more food. You see they will tell you when they have enough or not enough by ph fluctuations...up means they are releasing water and using food and if it goes down they are releasing water and using food, adjust accordingly. If you are running a tds meter in there and you got more than ten plants..and a reservoir of say 60liters...I ususally run around 1600ppm when in water. Also co2 will affect ph too...


keep in mind that it is not a good idea to keep pounding up and down ph too the water to correct because u will be in for trouble...instead use it as a temporary solution while keeping an eye on what you are doing. Adding fresh water will up ph, adding a little food will down ph...you want it even.

Thanks,
That does help, except when you said "up means they are releasing water and using food and if it goes down they are releasing water and using food, adjust accordingly." - it sounds like the same thing - was this a typo? was up supposed to mean something different then down?

with fox farms the ph will go up when they eat the food and use less water, and down if it is vise versa, With my experience also rez temps will affect ph that is why it is good to get a meter with automatic temerature compensation. Alsthough temp does not affect that much