I finally managed to get a Red Sea reef care master kit and tested my green spotted puffer's FOWLR tank - not bad considering I've been relying on Salifert ammonia and nitrite kits, API freshwater high range PH and nitrate, and no KH test since it was set up 5 months ago but far from perfect. Ammonia just over 0 maybe .05 or .1. Nitrite just over 0, maybe .025. Nitrate 20 which is ok for FOWLR but clearly why I have hair algae and cyano although this is going down. I do plan to add some soft corals so it needs to come down a lot more. PH 8 so a little low, KH 9 so within range but not by much, also could be higher. This is their starter tank, 35 gallons with internal filtration as well as live rock, no skimmer at the moment. They will be upgraded to a 110 gallon tank with a sump, refugium, skimmer, and pump later this year or early next, when they reach about 50% full adult size so a lot of issues will be ironed out then. In the meantime I do weekly 25% water changes and grow macro algae in the tank, do you lot think a small hang on skimmer would help get ammonia and nitrite to absolute 0 and reduce nitrate a bit? The tank has to be tightly covered as I have 6 cats and as much as I don't want the puffers eaten it would also be the end of the cat as they have toxic flesh. I've been told PH and KH are lowered in covered tanks as gas exchange is hindered, I have worked out an exhaust system to address this without endangering the fish or cats with an open tank. While they are getting a proper marine system soon I want to ensure they are healthy, happy, and safe in the meantime. Do these measures sound workable? anything else i should consider? Lol tomorrow I'll find out how my 2 month old reef tank at work is doing chemically and probably have a load more annoying questions. Many thanks for any input!