if you need to move in june wait until june and wait till you get a bigger tank. There are stickys on this forum that are the basics to stingray keeping. Canister filters are suitable but considered bare minimum for stingrays. Fx6 may say rated for 300 gallon but it wont keep up with what you are feeding. especially since the flow should be atleast 7-10 times size of your tank. people keep tankmates with stingrays yes, but its not required, or suggested. A suggested tankmate would be silver dollars, toilfoil barbs, and/or a semi large catfish. NOT PACUs. NO PLECOS. these tankmates are normally used as cleanup crews for the mess that stingrays make when they eat. food is also on a sticky. read it. acclimation is normally done by drip system and isolation tanks. Get a hospital tank, drip them with airline hose to acclimate the water. i normally drip mine for atleast 30 minutes and most people think its too little time. 45-60 minutes is the norm i believe (dont quote me on this). Feeding depends on whether your ray is wild caught or tank bred. If wildcaught and bought from a LFS 90% of the time it will be skinny. it's weight will just be enough for survival. Start feeding it foods to gain weight (in the sticky again). IF its from a breeder they will normally tell you what they eat. just supply the same foods. Dont try to break them till they are fat. (again sticky). as for my last tip i can not stress enough about filtration. cascase whatever or fx whatever will be bare minimum. 7-10x the rate. New hot thing is moving bed filter with k1 kaldness or the knock offs. research it. most of us if not all of us overkill the filtration. there is good reason why too. Get rid of everything exept the silver dollars, save the money and get a real tank. KH and GH normally dont matter unless you have teacups/retics/hystrix rays. they are a little more delicate. Motoros are hardy, but grow huge. you prob will try to get the bare minimum size tank possible for your rays. so you'd prob max out at 300 gallons. unless you have atleast 3-4 feet of width, no ornaments. no driftwood. sell that too. substrate or no substrate your choice. most prefer no substrate as easier to clean tank. one thing on food you may not see in the sticky is go look up foods with thiaminase. keep a list of it. these are the foods you avoid. good luck.