I have a much harder time keeping pH consistent with RO water then with water out of the tap. With 18-20 gallon bubblers, I have to adjust pH down every day. The larger the reservoir, the less it needs to be pHed. This is one of the reasons I went with a large recirculating dwc settup. Complicated to setup, theoretically easy to maintain.

PS. Having grown 2 to 4 plants per 20 gallon containers I will never put more then 2 per 20 gallon container and I will train them away from eachother. DWC has explosive growth. I was given a 4 plant 20 gallon bubbler and it was a dissaster, even after flowering immediatly from clone.
Racerx Reviewed by Racerx on . PH Dropping quickly? I'm sorry to post this question, I tried to search but the term "PH" is too short for the boards search function... I'm having to PH Up my nutes more frequently as my plants grow. I'm wondering if this is considered normal, or if it is indicitive of any actual problems etc. I only use 8 to 10 gallons or so total (going to change it out and measure carefully today) and the plants are only about 10 inches tall, on their 8th node. I calibrated my continuous meter yesterday, and PH Up'd to Rating: 5