can I use lava rocks?

[GregB]

Hi,
I wrote to you about two months ago and ask about the 4" pvc pipes, Well I did it! I am using clorox bottles and I have two questions 1: can I use lava rocks? will it screw up the ph? 2: I have tomatoes and peppers, hot and bell, how often and for how long should I set the timer to water using the drip system?
I have my tank below ground level to keep the temp. down as it gets quite hot during the day here in Fort Lauderdale Fl. I am using General Hydroponics FloraMicr and FlorGro. Thanks for your help and web page!
Greg B.

[Ron]

Hi Greg You have to make sure the lava rocks have been sterilized because of the toxins that pure lava rock has. I would water every 20 minutes or so for 5 minutes and maybe more often as the plants get bigger or it gets hotter.
Ron