I have never used crystal sea marine mix. I am used to Instant Ocean. I do recomend it as a easy salt to use and get used to. It is for one thing very consistent and does very well by me. If you are talking about the the aqurium phamecuticals test kits. They are not bad kits, just not accurate enough for reef use, to me. Like has been said before Salifert is the way to go. The kit if it is what I think it is, you have to wait 5 minutes to read it. Here is the trick. Mix up a water change worth of water with your salt. Test the water you are going to add salt to, write it down, add the salt and let it stabilize, test it and write it down. Then test the water in your tank and write it down. For example you have 10 gallons of rodi water, testing 0 nitrates, you mix up the salt and it tests 10ppm nitrates, you test your tank of call it 50 gallons of water and it has 20 ppm nitrates. So when you to a 1/5th water change you take out 4 ppm nitrates and add back 2ppm nitrates. For a net after change of 18 ppm nitrates. Doesnt sound very useful. Test those parameters I gave you. Write them down, and post them. Now I think you can see why people recomend rodi, and high quality salts. If your using tapwater and your salt is high in nitrates you are always going to have a high reading. Hope this made some kind of sense anyway. Oh yeah and if you have bioballs, and no fish or corals yet, They make great cat toys, or give them to someone with a fish only system. Not for you if you want corals. Steve
