koi pond, algae, dark pond


Old 08-02-10, 02:00 PM
Thread Starter
Join Date: Aug 2010
Location: U.S.A.
Posts: 2
koi pond, algae, dark pond

we moved into this house 1 yr ago and it has a beautiful 700 gallon koi pond with 3 koi. we knew nothing about koi, so we've been reading some books, but are struggling with keeping the water balanced.

out test strips say all is normal, except pH is low. Everytime it gets hot (eastern VA where it's been over 100 degrees this summer), we get long stringy algae and the sides of the pond are covered in algae.

when we got back from vacation, our largest koi had died.

we've used an algae killer - didn't work
tried liquid treatment to add beneficial bacteria and oxygen - did nothing
we have a UV light, but I've read that does nothing for algae

The lady at Petsmart told me to order Clear Pond's Crystal Clear bag of granules, so I did that but hasn't arrived yet.

Any advice is appreciated.
Sponsored Links
Old 08-02-10, 08:01 PM
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 18,554
You mention adding various chemicals to the pond but do not mention if the pond has any filtration or aeration.

When temperatures climb low oxygen levels in your pond become a major concern. Warmer water can hold less oxygen. You need to insure that the pond's filtration is working properly and that you are oxygenating/aerating the water.

Don't freak out about algae. It is very natural and is living off of excess nutrients in the pond and most algae are helpful (though not attractive). There is no simple "add this chemical" that provides a lasting solution to algae that is safe for pond life. You have to be especially careful using algaecides with koi. Many are safe for other fish species but toxic to koi.

Trying to kill algae during the heat of the summer when the ponds water is holding a minimal amount of oxygen is doubly bad. The algae was producing oxygen, helping the fish. So, when you kill it you remove on source of oxygen. Then when the algae decays it consumes oxygen from the water.

A UV sterilizer will help control algae when used properly. Do you know how old the bulb is? The bulbs loose their power over time and need to be changed at least once a year even if they continue to lite. Has the sterilizer been cleaned lately? Scum builds up on the interior and blocks the UV from reaching the water at the proper dose.
Old 08-22-10, 05:15 PM
Join Date: Aug 2010
Location: United states
Posts: 1
Avoid Chemicals

You should always avoid using any chemicals in your fish pond. Chemicals don't need to be used in a natural ecosystem. All you need to do is control algae, you don't want to get rid of it. A uv starilizer is the best way to do this, along with a good biofilter.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes