If you are keeping koi, a ph of 8.0 is fine. My koi pond is a steady 8.2. What you want to achieve is a ph that does not fluctuate more than a few tenths. If your pond is normally 6.5 to 7.0 you could do a 10% water change once a week and see if that brings it down.

good to know barbwire. Thanks

I was told that you could lower ph using peat moss inside a panty hose. I've never tried it myself though. We have naturally high alkaline we have goldfish in an aquaponics set up and they are doing just fine.

You're the 2nd person to recommend peat moss. Maybe there's something to this. I'm gonna give it a shot. Thanks littlemonkeys.

Oh I forgot to mention it will likely turn your water brown though from the tannins, but supposidly is ok for the fish. You can also try muriatic acid. We used to have to use that for our pool.

Brown water's fine, but muriatic acid? I guess it makes sense. a more condensed mixture of the acid is what I use to bleach wood.

If you use the acid make sure you add it to a bucket of water first and then add it slowly a little at a time. I'll be having to deal with this myself on a regular basis since we're planning on converting our pool to an aquaponics system so if you find any other ways to deal with high ph please post since our water is even higher ph than the fish tank. The fish actually help to lower the ph some.

Will do

Be sure to test your water using test strips such as these. Also, having more plants helps to balance out the eco-system and in turn should help bring your pH down.