Here is a picture of the new Kalk reactor I built to work in conjunction with my auto top-off for my 58g. This is a Vortec Reactor that only adds saturated kalk overnight when the ph needs to be boosted. It stirs an hr after the lights go out and when the ph starts dropping, it adds the kalk via drip method with an aqualifter pump and float valve. It starts adding kalk when the ph drops below 7.9. The rest of the time it only adds ro/di. It has a clear viewing tube to check for re-charging.