I finally completed my new larger pond to accomodate my growing koi but they are not doing very well in it. The pond is 3000 gallons, made with pvc liner and a waterfall pump of 1800 gph. I've got a biofilter waterfall, which I seeded with media/filters from my old established pond. The pond has been running for 10 days now, and I put 5 (6)inch koi in about 5 days ago. I use well water, and it's ph is naturally around 6.5 On day 3 of having the fish in it, I had some trace amounts of ammonia and I did a 20% water change. Day 4, the nitrites went to a trace of 5 so I did another 25% water change. This morning when I checked the ph had risen very high (over 8.5) which was as high as my color chart went, so I did a 75% water change which dropped my ph to about 6.5 and I had to add baking soda to bring it back up to about 7.0. I've salted the pond to 2%, but my fish are hating this stress - they lay on the bottom and sometimes fall over. I give them antibacterial food only once a day, no other feeding. I've corrected the water params so today my ammonia is 0, nitrites is 0 and nitrates is a trace amount, and ph is at 7.0, but my fish are still floundering. I could move them back to my old pond, but its so small (500 gallons) and I'm worried I'll just stress them out even more. The only thing this new pond has different is the presence of bougainvilla leaves which have fallen in the pond, but I net them out daily. Any insights or suggestions?
Thanks,
PONDerosa

Did you have these pH fluctuations in the old pond? That is really odd, unless it is the bougainvillia leaves. Is it possible to use a net to prevent the leaves falling into the pond?

I don't know but it might be best to move them back to the old pond and give this new pond a few weeks to mature/settle. Then start with just 2 fish and see what happens.

A high ph is fine, as long as your ammonia isn't high that can be deadly. Low ph is your worry, especially where it dropped so much. I think one problem is a lot of water changes, plus of course your ph going down to 6.5. I'm no expert but what I'd do is get salt up to at least .3% this does two things, it helps get the oxygen level up which is important for stressed fish especially, plus it helps protect the fish from ammonia which may rise in a new system. This can help you out with not having to do such drastic water changes. Remember that the salt helps build up the slime coat on the fish which will protect their gills from burning from ammonia. This doesn't mean over 0 on ammonia is acceptable but since your starting this new pond it'll help you get by until your bio filter is doing it's job properly. You also may want to get some microbe lift theraP which not only helps build up those needed microbes but will also raise your oxygen levels.

If you have some place to place a basket full of crushed coral this will help buffer your ph. I'm not too experienced with the coral but from what I understand it is supposed to keep your ph steady. You should be able to find it at your fish store, they usually use it in salt water tanks. You'll want your water to run through it, maybe at the top of your water fall if it can fit in there?

Scott

Thanks for the good advice about the ph buffering.....I did so, and it helped stabilize it. I finally recognized what was ailing the fish - fin rot! They started flashing and I saw an ulcer on the caudal fin of my largest koi. I had already raised my salt to .3% a few days ago, so I followed the advice on Koivet.com and did my first treatment for parasites with potassium permanganate today. I've had great success with this in the past (as long as you follow directions VERY closely!). I'll keep you posted if there are any adverse affects.

I'm not sure if they told you on koivet but if you put hydrogen peroxide on the fin rot and ulcers it will kill what ever is on that area and the fish will hill faster. You can also make a paste out of the PP and put in on those areas, only problem with that is it's cause a dark spot on the fish where ever you put the paste. PP scares me so I rarely use it. Wow if you add just a little too much it can be tragic. Let us know how everything turns out, a happy ending is always good to hear about and since you had success so far with PP I think your going to have good news.

Scott

So far so good on the use of potassium permanganate for the fin rot. I did the treatment exactly as the directions stated, which I got from Koivet. I don't go into detail here because, short of reprinting the whole set of directions, this IS tricky stuff and not to be used lightly and I wouldn't want to see a novice not give it the serious attention it deserves. I could see my fish were going to die unless I treated them and luckily I have PP on hand, along with antibiotic food.
Its scary to look at, but the infected areas have turned black and started to heal. I finished the final treatment today so they can hopefully rest and my water can get back to normal. The nice thing about PP is that a couple days after the last treatment the water is perfectly clear and prettier than ever. I had one fatality before I decided to use PP, and I wish now I had realized it was fin rot sooner so I could have treated sooner, but at least the rest of my collection is on the mend. I'll keep you posted as to their progress!

PONDerosa

Sounds like great news. Yes PP scares me greatly. I would use it only as a last resort. Ans like you statedit is important to do each step exact. (I'm just thinking it doesn't hurt to re-iterate incase someone skims through your post or mine).

keep us posted, I am sure more good news is to come as PP sterilizes everything. Did you take your bio filter out? Just curious I'm sure you did.

Scott