Need some help Ph swings...

[The Corsican]

Hi,

Check out these Ph and EC readings since this morning:

Date: Thursday, October 22, 2009
Time: 9:05:04 AM
Res: DWC 1

Starting Ph - 6.45 EC - 89 PPM (9:05:04 AM)
Adjusted Ph - 5.69 EC - 314 PPM (9:15:42 AM)
Nutrients Added - Two teaspoons of FloraNova grow. (9:15:42 AM)
Checked Ph - 6.39 EC - 297 PPM (2:16:44 PM)
Adjusted Ph - 5.61 EC - 739 PPM (2:21:55 PM)
Nutrients Added - One teaspoon. I added back 1 gallon of Spring water making the overall PPM 739 (2:21:55 PM).
Checked Ph - 6.14 EC - 351 PPM (8:46:16 PM)

Res Temperature: 70 - 75
Ambient Temperatures: 77 - 79 degrees.
Relative Humidity: 42% - 46%

The Ph is going all over the place in my opinion. I understand that the Ph rises when the plants eat but I thought it was a more gradual process? I'd like to see the Ph stabilize a little bit at least. What do you think is going on? I'm using spring water in this DWC unit. I'm using tap in another unit and I'm still seeing similar Ph swings. The only difference is the PPM's have stayed the same in the other res, the plants aren't feeding at the moment.

I'm using FloraNova veg nutes right now.

Thanks.

[v3d4]

how big is your plant(s) and how big is your reservoir? typically i think this will happen when your volume of nutrient solution is small compared to the size/amount of plants drinking from it. if you have a 4 week old plant in a 5 gallon reservoir then i dont know what is causing that, unless you are getting false readings from a bad Ph/EC meter. - but thats just a guess

[The Corsican]

I think you're right.

My res is 7-1/2 gallons (water volume) and a total of 14 gallons all together. A buddy told me the same thing last night. I have five plants growing in my res.

Thanks man.