distiled water will be great, ro/di water is just super filtered, distiled water is water in its purest form, the earth, ocean/lakes ponds rivers all evaporative, clouds form water condenses in the shy and falls down as rain, thats distiled water on a large scale, now if all equipment is clean it should read 0 tds as with ro/di water. I use distiled water. I had the typhoon from air water ice and i now use my own distiler to make water. I think its a matter of choice. @ walmart the "filtered" water is about .33 per gallon here south of you all, and last time i check the distiled water is .75-.99 a gallon and you a plastic gallon jug out of it. I am not tell you distil is better than ro water but just test it for yourself to find out what would work for you. Some say ro water is needed for coral but i seen people use tap water with only the carbon filter and i seen people also use ro/di for tanks with fish guess it comes back to a matter of choice, GL in looking for water that fits your needs and i hope someone else can use this info i put out.