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ATO & Dosing Pumps

What is an ATO? An aquarium Auto Top-Off system measures water levels in the aquarium or sump. When the automatic top-off sensor detects a drop in water level, a pump sends fresh water from an auto top-off reservoir into the tank.

The best auto top off system, like the Tunze Osmolator, will have multiple sensors and fail safes to prevent flooding. A good nano auto top off, like the AutoAqua Smart ATO micro, has all this in a tiny form factor that fits in an all-in-one nano. A kalkwasser reactor can be attached to an ATO to replenish Ca and Alk in a reef aquarium.

An aquarium doser, like a peristaltic dosing pump, delivers small amounts of fluid in timed intervals. The timer is tuned to deliver elements at the same rate they are depleted. A reef doser setup will often have at least three pumps (for Ca, Alk, Mg).

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ReefBreeders Prism ATO Auto Top Off System
X1 PRO WiFi Dosing Pump - Kamoer
JBJ Nano ATO Auto Top Off System with Pump
ReefBreeders EXO ATO Auto Top Off System
Bubble Magus BM-T11 Dosing Pump
Bubble Magus BM-T11 Dosing Pump Package



Trigger Systems Crystal ATO Reservoir Tank - 10 Gallon
Bubble Magus Tube Holder


Bubble Magus Dosing Pump - BM-T01
Bubble Magus Dosing Bracket


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