Wednesday, October 20, 2010

Premium Accudoser II Peristaltic Doser Pump

Model PA-AD

A User’s Review

By Jim Dantin

Another doser pump is on the market. Premium Aquatics of Indianapolis, IN http://www.PremiumAquatics.com has entered the market with a private-labeled peristaltic pump that is designed specifically for feeding additives to your system. This pump looks quite similar to the “Drews Doser” that is sold (but perennially out of stock!) by Bulk Reef Supply. It is designed to connect to standard airline tubing as a simple and inexpensive way of feeding liquids between supply containers and your system.

There are many peristaltic style pumps on the market for aquarium use. The design has been a standard in the industrial and medical fields for many years. Because of the design, chemicals never make contact with the pump itself – the peristaltic motion squeezes a piece of tubing to force measured doses of liquid to flow through the system. Depending on the composition of the tubing you can feed chemicals that would otherwise cause buildups or damage to conventional pumps.

You can easily change the tubing as needed to prevent cross-contamination – for example allowing you to use the same pump for dosing of medicine into a hospital tank without danger of contaminating your display tank. All you have to do is swap out the tubing set – much like what happens in a hospital when they change medicines or patients.

Some of the previously-sold pumps left a bit to be desired for the aquarist. The pump design should provide a smooth pumping motion and prevent back-flow or siphoning. This new pump has four stainless steel rollers – a substantial improvement over other pumps’ two or three roller designs. This pump does require removing two screws to change the tube – a bit less convenient than some other designs, but needed to control the forces exerted by the 4-roller design.

I have used the Aqua Medic pump for years. It has two plastic rollers on a thin plastic frame. I have experienced cracked frames, and wear in the roller pivots. The new pump is a much more solid design that should give far less problems with use.

With the Aqua Medic pump, I had to install small one-way valves in the water feed line or the pump would lose its prime and not work consistently. The new pump shows no inclination to backflow or lose its prime. It successfully pulled water out of a supply container into a dry feed line – my Aqua Medic could never accomplish that – I always had to pre-fill the feed lines before the Aqua Medic would pump!

This pump can also control the feed of liquid from a supply that is located above the pump – with other pump designs, you would risk a continuous siphon of liquid when the pump was not running and a roller was not pinching off the feed tube completely – the 4-roller design eliminates that risk. Note, however, that it is not intended to be directly connected to a pressurized water source such as the output of your RO/DI system.

One “feature” of the pump that may seem strange is its low feed rate. It is rated at 1.5 mL per minute. That is a very slow feed rate that you can observe as drops rather than a stream. This prevents use of the pump for makeup water – but that’s not what it is sold for. The pumping rate is very constant.

I tested the pump by measuring the output into a lab-grade graduated cylinder. After 20 minutes of pumping, I had exactly 32 mL of water – a rate of 1.6 mL per minute. This is a bit more than the advertised 1.5 mL feed rate, but well within what one would expect in a consumer-grade product. You should run a similar test before using the pump for any sort of critical dosing use.

Because of the slow feed rate, you can easily control how much chemical you dose into your system by using the pump with the inexpensive timers that are found in home supply or discount stores. These timers typically have on/off cycles that can’t be shorter than 10 or 20 minutes. This would be a serious problem with a higher flow rate pump – but not this one.

It is a simple calculation to divide the amount of additive by 1.5 to get the minutes of pumping time. If you want to dose 120 mL of additive a day, set your timer for 120/1.5 or 80 minutes – this could be spread out to eight periods of 10 minutes each or four periods of 20 minutes if you want an even more steady dose.

The design of the pump also provides a very high head pressure that allows accurate pumping many feet above the pump’s location. The pump is rated by the manufacturer for a 25’ head – I was not able to test this extreme lift, but it should easily handle pumping from a basement utility area up to a first floor display tank should you need to! On a more normal application, this means the pump’s feed rate would be relatively immune to locating the pump above or below your sump or display tank.

Overall, I am quite pleased with the pumps and can see using them for many applications in my setup. Premium Aquatics stocks both the pumps and replacement tubing kits.

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