When I first began thinking of setting up a large aquarium, I knew one of the top ten items I wanted was an auto top-off system through which I could also dose kalkwasser. I also knew I didn't want to spend a fortune for such a system. I considered a float valve, but that would require drilling the sump. The Reef Tank suggested the Spectrapure Power Liquid Level Controller. This is an extremely easy setup, very inexpensive, and is working very well!

The LLC consists of a probe which attaches inside your sump via suction cups. Airline tubing runs to a small box which contains a solenoid and an electrical outlet into which you plug a small pump (I'm using a RIO 800). The pump goes into a reservoir (a 5 gallon bucket in my case) and tubing for the water is run from the pump back into the sump. There is a small valve in the probe which sends air through the tubing to the solenoid when the water level drops and the solenoid then turns the current to the AC outlet on. As the tank fills, the air in the tubing is displaced, turning the solenoid and AC outlet off. When the current is on, the pump turns on, pumping water into the sump from the tubing attached to its output. The actuaction level is plus or minus 1'.

I'm using this system to not only replenish evaporated water, but to dose kalkwasser. I fill the 5 gallon bucket with RO/DI water to which I add kalkwasser. I wanted to use a small diameter tubing from the pump to control the rate at which the kalkwasser was added to the sump. I accomplished this by using the gate valve on the pump. I turned the valve off and inserted it backwards so that only the venturi would get water flow (this did require filing down that end a bit to make it fit into the pump). I then attached airline tubing to the venturi, so the water flow is much slower than it would be with normal size tubing.

This entire setup can be accomplished for around $80.

MODIFICATION:

In September 1999, I experienced a problem with the kalkwasser doser. The pump was sitting at the bottom of the bucket and pumped a large quantity of kalkwasser sediment into the sump (it was an actual 'pile' of white). This clouded the tank to the point that it appeared a snowstorm had taken place - glass, powerheads, sea urchins, you name it - were covered in white. The alkalinity in the tank plummeted to 3.2 dKH.

In order to prevent this from happening again, the handy guys at The Reef Tank constructed a stand to fit into the bottom of the bucket and keep the powerhead suspended above any sediment that may form. They took a piece of white plastic eggcrate (available at any hardware store) and cut it to fit into the bottom of the 5 gallon bucket. They then cut 4 one inch lengths of PVC pipe and attached them to the eggcrate with plastic cable ties to make 4 legs. I placed this in the bottom of the bucket and sat the pump on top - any kalkwasser sediment now sits below the level of the pump and remains in the bottom of the bucket.