Those filtration systems are only suitable for drinking as it's only sediment and carbon for 2 stage and some only have 1 stage. You can use a TDS meter to test. it will probably give you a reading of more than 20 as such systems do not have DI media which strips yr water off everything. For sps tanks, reefers wouldn't settle less than 5-7 to keep nutrient low; however, if you don't want to invest in 4 to 5 stage ro/DI systems, you can use chemical conditioners to "soften" tap water. Do some research on designing yr tank if you are going with custom build. If you are buying the tank Off the shelf, then you're better off with an iOS system. What equipments will you be using? what are you using for nutirent export? protein skimmer, underflow algae scrubber, refugium etc. There are tons of info in the forum. I may be imbarking on a small tank size build so doing some research myself. These are the type of questions I ask myself. Also, what is yr budget? Btw, FR stands for fluidized reactor. Use a FR if you have a sump. If not, you can use filter bags containing po4 removal media if you are having an IOS system.