Lets Talk about the water. RO water, which is likely what the "refillable water" is (I suggest you verify that) would probably be sufficient. Ive used the same thing for the past 15 months. The downside to using this is that you have no way to verify the maintenance of their filtration system. You will likely pay about $0.33 per gallon for refillable RO. If you calculate the rate of evaporation and the amount and frequency of your water changes, you gan get a good estimate on your water needs for 1 year. As an example, I have a 55 gallon tank with a 30 gallon sump. Over the course of a year, I loose an average of about 1.5 gallons of water per day. That coupled with 25 gallon water changes monthly, I use approximately 950 gallons of water per year that cost me an annual expense of just over $300.00
Now, for less than half that, you can purchase an inexpensive 6 stage RO/DI unit on ebay. You save money, get cleaner water, and you control the maintenance of your system. I plan to be purchasing one in the next few weeks. Ive got several friends using these systems and have heard no complaints.