I guess I will ask this question here even though I could just as easily ask it in the FW beginner forum... But since I am researching for my first SW tank and I think accuracy seems to be more critical with SW tanks, (notice I said "I think" because at this point I know very little) and in my research I came upon the Hanna phosphate checker for checking the phosphate level in your SW aquarium http://hannainst.com/usa/prods2.cfm?id=045001&ProdCode=HI%20713 and I found this to be a very cool little instrument for not so much money when you stop to think what it does. Hanna Instruments also has identical devices for checking the following the things. (some of which I have no idea why you would want to know...ie color) Color, Silica High Range, Free Chlorine, Nitrite Ultra Low Range, Phosphorus Ultra Low Range, Calcium, Total Chlorine, Phosphate Low Range, Iodine, Iron, Alkalinity, Nitrite Ultra Low Range, Phosphate High Range, Phosphorus High Range That got me to wondering what other tests there were out there that could be done digitally. I have such a hard time trying to decide exactly which color on the color chart is closest to the one in my little vial when I am doing tests with my API test kit for my FW water tanks. Luckily in FW we don't mess with PH and since Ammonia and Nitrite are always (supposed to be) 0. The only reading that changes much is the Nitrates and the FW fish tolerate a fairly wide range if you compare them to their SW counterparts. But... As I was reading a sticky in the SW beginner forum I noticed I would need a High Range Test kit for Nitrates and began to wonder if there were a digital test kit out there. Now wouldn't that be nice! I did not find one. So if anyone knows of one... Please do share the information! I did however find that there is a device that measure the electrical conductivity of saltwater. I don't exactly understand how that is useful to SW tank owners but I understand it is. They start in price on Amazon from as low as 19.99 for this one http://www.amazon.com/Digital-Quality-Measurement-Resolution-Accuracy/dp/B00KSTZGNE/ref=sr_1_3?s=hi&ie=UTF8&qid=1405716605&sr=1-3&keywords=electrical+conductivity+meter+tester There was one for a few cents less but since it looked like it shipped from China and had some reviews that were not so good, I passed it by. There are many more and they go up to over 200.00 in price. But according to the few reviews the cheap one seems to work. Does anyone have one of these devices? If so, may I ask which one you use and exactly how is it helpful to you to know the electrical conductivity of the water? Maybe this next question should be in another thread but I keep reading that the PH is supposed to be above 8 for SW tanks and I also know that RO/DI water is usually used... Isn't that water usually a lower PH? That equipment I already have but I am only using the RO portion at the moment and have not installed the DI membrane as I didn't need it yet... How do you get your PH back up? Thanks for any information you can offer me. Also if you could offer any advise on up to date books that I can read. Then maybe I won't be on here bugging you too much.