View Full Version : Ph down fears

06-16-2010, 11:21 AM
Our water is so hard we have to use RO. When a fresh batch of nutrients are mixed up the ph will be about 6.5 and 3 cc of ph down will take it to 5.5. in the 55 gal Ebb&Gro. Now here is the thing, after one cycle or two the ph will be over 7 and climbing. After two days the Ph will be 7.5. Now 6cc of ph Down will drop it to about 7.1 My question is just how much ph Down can we use and not harm plants? Can we use as much as needed to get ph to 6.0 without fear of harming plants?

Thanks in Advance


06-17-2010, 11:36 AM
- what kind of hardness readings are you seeing at your source water? both before and after being processed the RO.

- which model RO system are you using?

if your hardness is more than 10 GPG, you should be using a water softner prior to filtering with RO. any hardness that was unable to removed by the RO membrane will continue to act as a pH buffer just as you are seeing.

also if the hydroton rocks weren't throughly rinsed, any clay dust in your reserviour will also raise pH. if you notice excessive amounts of clay silt at the bottom of your reserviors, this may be the problem with your pH levels as well.