November 26, 2015

Pond Q&A 11-26-06

Today's Pond Q&A

In this issue:

- Chlorine Poisoning

- Hail Storm Damaging Koi?


Question #1>

Hello Carolyn,

My wife called earlier today. We lost all our fish last night. All
floating today, about 12 adults plus some babies. (Just goldies,
but some were 5-6 inches and we've had them in the pond for a year
and a half.) Several have blood leaking from their eyes. The water
temp is about 60 and she has been feeding lightly. She did
discover the pond was overflowing because the level control valve
was stuck. It was OK on Sunday when I checked it and she didn't
notice it running yesterday.

Too much city water? The level controller (horse trough controller)
usually just bleeds the waterin to match evaporation so we don't add
much water prep, I'm afraid. Yesterday she noted that essentially all
of them were down in the deep "refuge" end of the pond and were down
deep just "holding station". Trying to escape the Chlorine?
Strangely, neither Plecostomus has floated up yet.



Answer #1>


If you have chlorinated city water, you should use a timer so this
doesn't happen. I'm sure what you suspect is what happened. These
controls do wear out since the movable parts are made of rubber and
eventually will rot. If you have a huge pond, no real harm will
come to them, but in smaller ponds we can inadvertently replace all
the water in a very short time. Perhaps the plecos are dead on the

They do make an automatic refill that sprays the water across the
pond, through the air, which will neutralize most of the chlorine
before it hits the water. I suggest you look into these or put a
timer on yours. If you even turn it on once weekly to top it off,
you should always use a timer. They are inexpensive, can be bought
at Home Depot or Lowes, and have saved many fish from toxic
chlorine poisoning.


Just send us 4 or 5 good pictures of your backyard pond
paradise along with a brief description of your pond
construction. Send your information to us at

Question #2>

Hi Carolyn,

I really enjoy reading your news letter, and as a result, always buy
from you first if ever possible. Thank you for helping educate
those of us who enjoy having a pond in our back yards.

I have a 750 gallon pond 3 feet deep with 5 Koi (about 12”long) and
it is elevated about 12” above the ground so I have no runoff
issues. I change 25% of the water every week or two and use a 1000
bioforce external filter ran by a 800 g/h pump and have a separate
2000 g/h pump running a waterfall. I have never used a U.V.
Clarifier because I have lots of water lilies (covering about 2/3
of the pond) along with other plants and the water is always
crystal clear, and I add Microbe Lift every month. Pond life has
been great here in South-West Colorado until yesterday. I fed my
fish before I left for work and all was normal in the AM.

We had a hail storm and some rain in the afternoon, and when I came
home in the evening; my fish were acting “off”. They kept to the
water surface and gasping almost like they needed oxygen. The hail
had riddled the water Lily leaves as well as damaged most of the
other plants, but all else seemed OK. I do have an automatic pond
filler that I made from a swamp cooler float and valve, but it gets
its water through a pond fresh PF100 chlorine remover. Even if
that failed, I don’t think the small volume of water added could be
a problem. I immediately tested my water and found the temp at 65,
Ammonia at “0” and the Nitrates at “0” and the afternoon ph at 9 (I
tested again in the AM and it was 7.5). The fish seemed to be
getting worse, so I did a 25% water change, and not trusting my in
line chlorine remover anymore, added chlorine remover. This
morning two fish were dead, and the other three still hanging
around the surface under the water fall. I did another 50% water
change. Now I think the other three are coming around. If all
works out well, I will do another partial water change tomorrow.

I have no clue what could have gone wrong! The two dead fish
showed no sign of trauma or injury, and the water still seems fine.
I don’t believe the fish would eat hail stones nor if they did that
it would cause any problems, but could it? I also wondered if the
damaged plants could have released anything into the water that
would harm the fish. I have been battling elevated pH all summer,
and thought I had it under control. Could the P.M. ph spike have
caused such a problem so fast? I can’t believe that was an unusual
ph swing.

I have had these fish for 3 years. As you know the advantage to
having few fish is that it makes the pond easier to keep in
balance, you can refer to your fish by name and you become very
attached to them. I am worried that this may happen again to my
other 3 and dislike the idea of losing 3 more of my friends. Do
you have any ideas or suggestions?

Answer #2>


This is not the first help call where fish were dying after a hail
storm. I can’t say the pH spike is related to the hail storm, but
my guess (and it’s just a guess!) is that the fish DID think they
were being fed and tried to eat the hail. That would rapidly chill
their metabolism and cut off their breathing and gill function.

It’s too bad that koi aren’t any smarter than they are. Being
conditioned to eat at the surface they probably took a beating too
and suffered some skull and head damage in the process. You won’t
be able to see the bruises sustained, but if the hail was big enough
and strong enough to tear up the lily leaves, the koi had to
have some direct “hits”.

The torn lily leaves wouldn’t do anything to harm the fish in that
short time. Only if they were allowed to rot would they become a
problem. If you had any poisonous plants in the vicinity which
were blown into the pond, that could also have been part of the
problem, not saying that it was, but something to look at. As for
the pH spike? I think it was the storm that clouded the sky. With
a loss of sunlight, plants take oxygen out of the water and put
carbon dioxide in, raising the pH. If you have a lot of plants,
this might account for it. It still seems like a lot. If you test
in the morning and again in late afternoon, you will know better
what the normal ranges are for your pond.


========== @SK Carolyn =================
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Happy Pondkeeping!

Brett Fogle
MacArthur Water Gardens

Posted by bfogle at November 26, 2015 07:46 PM