If you dont have a meter I would check out the Hanna 9044 cheap and does it all. Very accurate. Better then any you will find in a grow shop at a third of the price. Check ebay or call Hanna for your local distributor. it 120 usd and does temp, ppm microsiemen ph and is a constant monitor so no worries about batteries. I have tested the ones in the shops and just dont get a truncheon they are a promotion for a company that makes expensive equiptment in new zealand are they sell them to the shops for 19 dollars. not worth the 120 they are sold for. I called the company to get answers about this expensive stirrer that would give me a lower ppm on both i tested when i would add 1000s of ppms. They are good for playing magician while scuba diving bout thats about it.
One love
c