You might want to get the Aquatic Life DI canister to go with that. It looks like the “RO Buddie” is just RO which will remove a lot of the impurities from water, but not everything. If you add the DI canister to it then you will have a full RODI system which will get the water about as pure as possible. The other potential option for you, depending on the size of your tank and the quality of your source water is to just go with a DI canister. DI alone will get the water to 0 TDS, but the issue is that DI resin can be kind of expensive. The RO membrane is used to remove a lot of impurities so that the DI resin doesn’t have to do as much work and it will last longer. But if you have low TDS source water and/or a very small tank then using DI alone might still be cost effective.