About Top-Off Systems Topping-off refers to the act of adding fluid to an aquarium to replace the amount lost to evaporation. This task is part of the routine maintenance which must be performed on every aquarium. Dosing involves adding certain amounts of fluids, usually chemical additives, in small doses to an aquarium over a period of time. The five main commercially available types of systems we have identified for top-off and dosing are: Drip systems - consist of a reservoir and some small diameter tubing. They drip liquid into an aquarium at a constant rate. The rate may be manually adjustable. Float valves - mechanical switches which are activated by the rise and fall of a float, in accordance with the fluid level. They work similarly to the float valve in the tank of a conventional toilet. They usually require a reservoir and some plumbing, which are supplied and assembled by the user. Some float valves require a hole to be drilled through the sump or aquarium in order to mount these devices. Switch & pump systems - usually involve a sensor, possibly a float valve, which switches on/off a powerhead/pump, which then pumps fluid from a reservoir into the aquarium, when its water level drops. Usually require a reservoir supplied by the user. Dosing pumps - a metering pump mainly used for dosing additves into an aquarium at a constant rate. The rate is usually manually adjustable. May require a reservoir and some plumbing which are supplied by the user. the NURCE - the only commercially available siphon-based system, consisting of a siphon and reservoir. Some of the features of these systems are compared in the table below. The "bubble" means that the feature belongs to some, but not all of the members of that group. Feature the NURCE Drip System Float Valve Switch & Pump Dosing Pump Replaces evaporated water Performs dosing function Replaces fluid at rate it is lost Self adjusts rate of fluid replacement No hidden costs No electricity required Simple set up Can operate beside sump, underneath stand All parts included for minimal operation Near zero failure rate No moving parts Large diameter tubing helps to prevent clogging No altering of existing equipment required Sealed reservoir prevents evaporation from reserve Can be used with any type of aquarium Other Features of the NURCE A large fill opening for easy filling and cleaning. A thick rubber gasket inside the screw-on cap provides a reliable, long lasting, airtight seal for the fill opening. Large reservoirs hold more than 5 gallons. Compact rectangular design easily fits into most setups. Made of ¼" thick clear acrylic sheet and PVC components, yielding a sturdy yet attractive device. Clear acrylic allows easy inspection of the fluid level inside of the reservoir. Fittings are securely connected to the reservoir and sealed. User attaches tubing to reservoir in a very secure manner. Device is reliable and long lasting due to secure connections and high quality components. Siphon should only need to be primed at initial setup. Can be used to dose Kalkwasser Mix. Reduces fluctuations in salinity for marine aquaria. What are people saying about the NURCE? If any of the comparisons made here are inaccurate, please tell us. Home | About Us | About Top-Off Systems | About the NURCE Pricing | Order Now | Contact Us | Links Copyright © 1998, 1999 Aqualan