Hi all, Here is a copy of what I sent to Jim, so you can see what I was talking about...
Looks fair enough, but there doesn't seem to be enough info available.
How many Kilos of media are you running?
What are the dimensions of the system?
What is the pond gallonage?
What is the flow rate over the Shower?
Is there other filtration?
Does the pond have bottom drains?
How much water is being changed? Are both ponds catching full sun?
What is the KH and GH of your supply water, and pond water? <END>
So... As far as systems are concerned, the pond should be turned over at 200% per hour minimum, with a one metre long set of Showers being flowed at 3000gph. This pretty much concludes that one set will filter 1500 gallons. But, if you choose to flow a set at 4500gph, this is great, but don't expect this amount of media (50 to 60kgs) to cope with 50% more pond capacity, as it won't. But, this higher flow method will basically mean that the pond will be turned over at 300% per hour.
Using another filter alongside the Showers will greatly reduce the necessity for a large number of Showers. Using something like static Kaldnes K1 for fines filtration (see
www.koi-uk.co.uk) works amazingly well, but only implement it is such a way that only about 25% of the ponds water is taken from the drains, through the static K1, and then over the Showers. The other 75% of the water drawn through the drains, is put directly over the Showers. This, I feel, is the best way to 'underflow' or 'undershower' a showered pond.
Water changes are necessary in the same proportion as a normal pond. But, I feel that it is best to trickle it in very slowly. Failure to change water will result in an increased TDS, and decreased KH. Contrary to popular beliefs, Momotaro's 1500 ton pond only has a minimal input of fresh water, nothing like the figures that I am told are being done!
Sunlight... This is a big issue, particularly if the water is clear. It will also hamper clarity in it's own right, due to algal growth on the walls of the pond, which will grow by day, and die of by night, or in bad weather, causing serious clarity issues. I feel that for the UK, a pond with about 60 to 80% shading to be ideal. And, it is much better for the pond to catch morning sun, rather than afternoon sun, since the ambient temperatures in the afternoon will be higher, which means that the sun will pick up the temperature faster in the afternoon. This kind of fluctuation isn't good. Too much sun will also damage the Beni of Koi, so bear this in mind.
Some people here in the UK are 'getting away' with as little as 100% turnover on a Showered pond. This is all very well, but with increased growth of the Koi, and hence, increased waste, these under-run ponds will soon reach their load limits. If you build a Showered pond, and don't stick to the design principles, you will eventually find problems with clarity, etc.
Mike.