Pumps for U/V clarifiers and clarifiers for filters

There is no doubt that filters seem doubly effective if they are working in conjunction with an Ultra Violet Clarifier or UVC. By passing the pool water through a container lit with a fairly low dose of ultra violet light, it was found that unwanted algae that made the water a green colour, clumped together and this made them more effectively filtered out of the system. UVCs need to be chosen to be compatible with the filter and the pump with different sizes and wattage of lamp available for different flow rates. It seemed to me that you could allow one watt of lamp power to treat roughly one hundred gallons of pool water, with a throughput of 50 gallons per hour through the lamp. But that may be simplifying things too much when you have sophisticated designs like the Hozelock Vorton U/V clarifiers and the Bioforce filtrations units on the market. Your retailer will advise you on the right clarifier for the flow rate from the pump.

The UVC must sit in processing the water from the pump before it gets to the filter. Some people like to use the outlet from the filter as the supply for a waterfall. This is feasible as long as the waterfall is allowed to run 24 hours a day, since the biological filter needs a constant supply of fresh oxygenated water. Filters are also more effective if the water is pumped from the far side of the pool, so there is a true circulation of the pool water. If the waterfall is very forceful, install the pump close to the where water flows into the pool, to minimise the disturbance to the pool environment. These are two considerations you will have to consider compromising when combining filters and waterfalls.

10 Considerations that effect your choice of pump

If you need a new pump, it will help your Aquatic retailer if you can be sure of what you want you water garden pump to do. Assuming you will want a submersible pump because they are the most efficient and cost effective for the price, here are a number of factors you and he will have to consider.

1.The cost arises before the pump is in place. Do you have power out to the pool or water feature? Doing the job properly with armoured cable and waterproof junction boxes can easily outstrip the mere cost of the pump. Also do you have RCD trip switches installed to isolate the pump from the domestic mains?

2. The above question leads onto safety, even though all electrical connections must be up to professional standards, many people with young children are still frightened of putting a machine running of 240volts into water a child might put its hands into. There is a huge range of low voltage pumps that can produce quite adequate performance for most domestic water gardens for very little extra cost and in total safety. You just need to find somewhere to put the transformer.

3. What do you want the pump to do? Will you want it to run a fountain, waterfall and a biological filter?

A biological filter needs to be fed the total volume of the pool every two hours. So you must know the volume of your pool. A rough guide is adequate:

(LENGTH x WIDTH x DEPTH) in metres x 1000 = Volume of the pool in Litres

The pump should be capable if pumping half that figure to an appropriate filter. If the pump is to run a fountain as well then you need possibly 1000 litres an hour extra for that. Gushing frothy fountains may need a lot more. Waterfalls need at least 120 litres per hour for each centimetre width to the required head of the waterfall. This translates to 60 gallons per hour per inch.

4. For filter pumps. Is it capable of handling solids? A fine sponge pre-filter may help protect delicate bearings but it doesnt allow much muck to get through with an all too regular wash out.

5.For filter pumps in particular, is it continuously rated? Does the guarantee cover it for running non-stop.

6. Fountain pumps with fine rose jets need a good pre-filter on the pump otherwise you are forever cleaning them out.

7. For waterfall pumps and filter pumps, looking on the performance table, is the volume of water you require to the height that your filter and waterfall header pool sits well within the 40% -80% of it maximum rated flow.

8. The costs of the pump can be easily outstripped by the costs of running it. A good motor that is capable of shifting 1000 litres and hour can be as little 15Watts.

9. Has it got all the fittings you need in the box? If you need extra fittings they can be quite expensive.

10. Is it easy to take apart and put back together again for ease of maintenance on a cold autumnal morning?