snipped and summarized below.

Hi Rick, Thanks for providing lots of in depth information about your pond.
I'm going to summarize to see if I've got it right:

1 yo pond
5400 gallons
Ammonia 0 (since that is the only safe zone)
Nitrite 0
pH 8.4-8.6
salt 0.8 (naturally)
11 Koi 5-11"
12 goldfish/shubunkins (yes, they can cross breed w/koi)
?# goldfish fry
Filtration: 2 Savio biofall filters. Savio skimmer, Sequence pump
4' wide waterfall
UV
Microbelift & Baraclear added.
Various plants, self-admittedly not enough

Is the PH level a main factor in the string algae problem?

In your age pond, String Algae is totally normal. As your pond matures it
will lessen. The only thing I saw that should be corrected is that 60%
water change. If you feel a big water change is needed, it is better to do
10% every day than a big one all at once. Why you decided on the big water
change?

Regarding the pH, yes, a high pH does make it harder for the other plants
to suck up the nutrients, unlike string algae that can thrive in it. Still,
if your normal source water isn't that high, in time your pond pH will
probably come down. So I wouldn't try to reduce it.

muriatic acid in very small and slowly disipated amounts to try and
bring my PH down.

If your pH was well over 8.5, I might consider it, but it does become a
maintenance ritual till things balance out... or the same result of leaving
it be.

What I'd recommend is get more plant cover, which you've already concluded
to do. Rake out the string algae as best you can, and this fall, cover the
pond with shade cloth, this will retard the algae from growing all winter
long.

Keep your water changes to 10%/week. If you feel the need for a large water
change keep it under 25%.

String algae is TOTALLY normal for a new pond. Prior to UVs, I use to tell
folks that if they put the maximum # of fish, for their size pond, in the
first year, they will have suspended algae, most of that year. The 2nd year
the water will be clear but they'll have string algae, and the 3rd year, if
they haven't done anything to kill the algae and start the process all
over, they'll have a healthy coating of fuzz algae on the sides, no bloom
(assuming they kept the fish population below critical mass) and little
string algae. UVs sort of jump over that 1st year.

Prescription, more plants and shade, along with a healthy dose of
patience. ) ~ jan


See my ponds and filter design:
www.jjspond.us

~Keep 'em Wet!~
Tri-Cities WA Zone 7a
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