What kind of filter system do you have? Is the uv submersible in-line?

Hi Waterwoman!

Until the pump broke Monday, he used the pool pump. It circulated and filtered the water. He also converted it to include a biological filter (changed out the DE fins to PVC filled with holey lava rock type things. That has been working for months.

The pump also runs the water past a tube with the UV light in ti. Not sure if that is before the bio filter or after.

We did see one lone tiny fish this morning but that was after watching for quite some time. He has/had some huge fish. The one koi that survived the winter under horrible water conditions is/was a good 18" or more long now. You can't miss him when he is the shallow water. Dh wonders if they are stressed and hanging out in the deep end where we can't see yet.

Buy a proper pond pump. Most of the pond store websites have them on sale this time of year. (You might want to stay away from the Aquascape brand. From what I've read on various forums, they break down after only a year or two.) Also Google Skippy Filter. You need much more than lava rocks, no matter how many gallons your pond is. Continue to use the uv; that's the best thing you've done so far.
I have an Alpine submersible pump, an in-line Pondmaster uv and a Skippy filter. My pond if 4,500-5,000 gallons and if I dropped a newspaper to the bottom, I could read every word. Once you have the right equipment and filter in place, the water will clear up. Good luck.

When the water is clear the hawk will come back to visit. I have to net my pond because our resident hawk and feral cat like sushi.

I just can't believe that the hawk ate all the fish in one or two nights. Especially when he could have done that before. And the pond is deep enough that they don't have to swim, and don't swim, close to the surface except when eating fish food. The pond is 3 feet at one end (covered with water lettuce) and 6 feet at the other end. We were just out there and did not see a single fish, although we heard what might have been a tail flip.

The water was perfectly balanced according to dh's strips. I know because he is color blind and I check it after he dips it. There were at least 15-20 fish in the pond on Monday. According to the strips the water is STILL balanced. They are also new strips.

Other than the fish on the deck (NO WAY it could have flipped itself out the distance it was from the water) and the fish with the perfectly circular concave hole in its side, everything has been good except for the algae.

A few months ago, dh also ordered a test to see if the water had any other stuff in there that shouldn't (chemicals, metals, other toxins, etc.) All tests were negative except bacteria which he knew would be positive because of the good bacteria.

Things are getting curiosier and curioser.

raccoons? A heron? Are you near a stream/river?.....beavers?

Not seeing anything curious or mysterious (twilight-zone-ish) here. I am, however, confused as to why you think 15-20 fish disappeared overnight when you plainly state you cannot see them unless they venture to the shallows (?) Perhaps the hawk made dinner of the koi but that's the least of your concerns at present.

Your best course of action is to stop treating *symptoms* and start correcting the root of the issue (unless you don't mind pouring a constant stream of $ into your pool cum pond).

Just for starters, what is your ratio of plant coverage to surface area? It's not clear how your dh converted the pool pump to include a bio filter. (I maintained a pool for many years & I just can't make sense of this - do you mean he's routed the flow through a filter?) In any event, IF it was working there would be no need to add packet after packet of 'good bacteria' as the filter would be serving this function without ANY help from you. You say "things are looking up" after adding (how many?) packets of bacteria? Bleh!

It's not unusual to experience a spring algae bloom (green water) but it's nearing the end of Aug now and you should not be experiencing green water. I'd suggest you go take a look at cliff_and_joann 's filter system. They've shared detailed schematics of their setup which you will find helpful.

I say again, stop treating symptoms and start correcting the underlying issues. Not only will your fish enjoy good health but your wallet will too,

blessings,
~digger

p.s. one last thought...toss the lava rock.

Duplicate post

This post was edited by kashka_kat on Sun, Aug 25, 13 at 13:41

Yes, same as what above posters have written. I suspect "two aeration bubbler thingies" are inadequate for proper aeration, oxygenation, and circulation of a 17,000 gallon pond... which is quite large and may require significant $$$ or some ingenuity to build a DIY system. The water circulation & oxygenation needs of a swimming pool (treated with chemicals) arent as critical as a pond which is meant to support plant and animal life.

Once you get mechanicals in place that can handle that volume of water and whatever degree of filtration is needed (based on no. of gallons, fish and bio load) then the rest kinda falls into place. You can add the "good" bacteria but they do need adequate oxygenation to survive and thrive.

Koi are known to jump out esp when stressed (such as a recent move) - no mystery there. The wound in fish could be a wound or ulceration from disease but as Digger stated you would want to look at the big picture and not the symptoms.

This post was edited by kashka_kat on Sun, Aug 25, 13 at 13:38

Hey there. I would suggest you try a better test system than strips. Due to many factors they can be misleading. A decent liquid test kit can be around $25-30.

Running more water through a UV system is not particularly productive. The water(and algae) exposed should have as long a dwell time as possible under the light. Perhaps the manufacturer should be contacted to determine the exact flow rate they recommend.

With such a large pond, it should be fairly easy to teach the fish to come to a certain place to be fed. How are you feeding them? Mine seem to be able to tell time.

Quilt batting is an excellent material for filtering out algae. I have mine in the Skippy filter along with an assortment of Scrubbies and crumpled up plastic netting that provides a home for beneficial bacteria.

We really could use more info on water movement in your pond.