Have got a 55w UV light but we have with the warmer water everything green again. Now think the UV is just enough the flow rate through it is too high. So I am planning to add another light. Saw post from Marius, on a smaller pond he runs 3x 55W I have only 1x55W.

Now the key question:
Do I get one additional 55W light, add that, i.e split the inlet in two water goes through both UV's then to outlet?

Or instead of getting a 55W UV light get two smaller ones and then split the flow 3 ways?

Any thoughts?

Adi

I would go for 2 x 55W. The price difference between a 55W and 30W unit is small ( about 30%)

With 2 x 55W UV’s you will end up with 110W of UV power compared to 90W for the 3 x 30W units.

Your maximum water flow for the 2 x 55W setup will be 36kL/h (18kL each) as apposed to 25.2kL/h for the 3 x 30W units (8400L each)

I think the efficiency will be more or less in accordance with the total watts.

I believe that for instance two 15watt UV's will have the same effect as one 30watt UV?

However, two 15 watt units will cost much more than one 30watt.

I would just add another 55watt and see what happens.

ok, will get another 55W thought if I split more, then the flow rate could be lower.....lets see.

quickly check with a calculator by added the second line of 50mm pipe, the flow rate drops drastically!

Adi

I know each setup is different but this is what I did. (Remember, I installed my UV’s before my filter chambers – had no choice since I pump-to-filters)

I use the valve to control the amount of water flowing via UV’s. You will be surprised now big difference it makes when I open the valve for water to flow from both directions. Mounted the 4 inlets to first chamber about 15-20cm above water level to add oxygen. My last chamber contains no filter media and I feed water to this chamber via 2 x 110mm pipes with bends. The waterfall outlet is about 30cm lower than the inlet and this creates plenty of bubbles.

Drawing of UV setup:

Mine looks similar now, although due to the flow rate etc, decided to do the filter first. Pump picks up from a large filter chamber (3 in a row), goes throw sand filter, then splits (t-piece), into 2x 55W and then joins again (T-piece) before going into pond.

Played around with a flow calculator yesterday, flow rate is half if you double the pipe diameter (now 2x 50mm)

Added the second UV this morning, hope to see a significant difference when I get home.

By the way cheapest and quieckest was Wilpet in Kempton Park for a 55W light.