Hi Tom
You’re absolutely right about hard water being better for sumi – this has been our experience here at Cuttlebrook. When Mark worked in Japan in 1986 he was told by Mr Kamihata and others that hard water made good sumi, green water made good hi and good living conditions made good shiroji.
Thanks for the links to Mike’s articles. He seems to be saying that the main benefit of softer water is better growth rates and that sumi and shiroji in particular are better in hard water.
Mikes conclusion:
CONCLUSION
There are two routes to take with hardness levels in your pond.
HIGH GH LEVELS
Good white ground and sumi development, but poor growth rates. (Ideal for those that are
hoping to show their Koi, or those that have less time to devote to pond maintenance).
LOW GH LEVELS. High growth rates, deep and even Hi,
but weaker white skin, and slower Sumi development. Bear in mind however, that just a few
weeks in hard water will improve the white skin ready for a Koi Show.
When we first read this article, some time ago, it was interesting as we had never come across any scientific research to support or otherwise the benefits of soft water. Now, we have the benefit of personal experience in this area and with 8 month old Koromo up to 28 cm and Chagoi at 55 cm at 18 months old in our own warm water growing on facility, I think we may be doing a little myth busting! (Our own water has a Ph of 7.9 at source which drops to 7.6 in the indoor tanks.) We are still in the early days with our warm water growing on facilities but I am sure that as time goes by, these growth rates will be pretty commonplace for our koi.
The only other issue is that of the quality of the hi.
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This picture was taken of one of our Kohaku just after it came out of one of our mud ponds back in June 2005. (It had never seen heated water and so had a totally natural growth rate and body shape). The type of hi that one looks for on a koi is to a degree down to individual preference. Some prefer a soft beni and others a deeper stronger red. It can also depend on the trend at the time. We’re quite pleased with the quality of the hi that we are producing.
Here is the same fish last year after it had spent some time in Sukoi’s pond, where it is currently growing on and seems to be improving all the time, thanks to Sue’s good pond management rather than soft water though. This would seem to suggest that there are many factors involved in maintaining good hi both environmental, dietary and genetic and to what degree soft water has an influence is still open to debate.
[img]http
://i100.photobucket.com/albums/m16/Cutt ... aDavis.jpg[/img]
We always listen to what others say and are not arrogant enough to assume that we know everything – there is always something more to be learned. All we can ever do is base our conclusions on either sound scientific research, or in the absence of that, our own experience and, rather like the Japanese, make the most of the water that we have available.
I imagine that the old soft water versus hard water debate will run and run, but in the meantime, we just keep doing what works best for us, which is all anyone can do really.
As for the sumi in the mud ponds, when we put our nisai back out in the mud ponds to grow on at the beginning of last summer, the sumi was really well developed but when we harvested them in the autumn, the sumi was not nearly as strong. As you say though, it does come back when we bring the fish back inside. It's the same water though, so there are obviously other factors at play here. A couple of theories so far are that firstly the high temperatures reached over the summer in the mud ponds have an adverse affect on the sumi and secondly, that the chromataphors in the black pigment cells are reacting to the colour of the mud ponds, making the fish paler. I am sure there are other factors at play too like perhaps water quality maybe. (These are just theories, they are not scientific facts!)
This koi breeding lark is quite complicated really isn't it? There's a bit more to it than chucking two fish in a pond and letting them get on with thats for sure!
Lisa