Hi all, sorry for the long thread title! Wasnt sure what to call it as i have a few questions!

Firstly, My spec

Pond water is around 2.5 months old. Currently have a stock of 25 fish all doing very well, feeding like normal and very happy! A mix of small koi and goldfish/comets, tench, blue orph etc. Even a frog sometimes! Have grown fantasticly over the time they have been in.

Pond is around 1600Gallons (i think). I run a Bermuda 10,000L phr pump into a filter box that i cant remember the spec of! A good one anyway!

I also have a hozelock 4in1 pump as a foundtain and built in UV light. The extrnal feed from this is open under water to create a bit of current to move the water around.

Unfortuntly the only info i dont have is any chemical readings, ph level amonias etc

My problem

Water was crystal clear until about 2-3 weeks ago. Then it went very green and now its so green i cant see any fish at all. only at the surface during feeding.

When i noticed this problem I bought the new burmuda pump (see spec above), was thinking perhaps im not flowing enough water, the hoze lock was doing 4000L phr on its own. So now im flowing up to 10,000L per hr, I cleaned out the filter elemets in the box using pond water. Got them looking respectable, they werent really all that bad anyway.

Still no alterations, just got worse. So i think perhaps its down to plants and the fact i dont have enough of them. I have now have 2 pots of lillys, some other various potted ones and lots of floating lettuce type things, around 17 in total! sorry plants arent my specialty! so plants are looking ok. could be better.

Now my thinking is that the pond is getting too much sun light, i have a south facing garden which see's sunlight from around 10/11am ish all the way through to 6-7pm. Summer at the mo!

It doesnt really get much shade. i think this is my problem, what are your suggestions?

Also what have you done to protect your pond from sunlight? I cant think of anything that will be a function, good looking solution.

i want to avoid chemicals if i can :) I added no additives what so ever. Fish get fed Once maybe twice a day depends on how lucky they are! ;)

Help, so down about it. really want it back looking good again!

tey some good by blanket weed. i had a similar problem when i set my pond up and this cleared it within 3-4 weeks. i know you dont want to use chemicals but the sachets do not harm the fish

you could also erect a gazebo type thing above your pond to dapple the light

http://littlepondontheprairie.com/yah ... pond408.113141728_std.JPG

ive ordered some crystal clear water clear stuff. should do the tricky hopefully, i may do a gazebo type thing for it. will see what i can design :)

If your pond is 1600 Gallons (7000 litres), your filter will not be man enough for the job.

It is recommended to multiply the pond size by a factor of 2 if fish are present and a factor of 4 if heavily stocked.

There are many factors involved in selecting a filter. I had to use a factor of 10 to get my pond to clear and I know people who have needed to use a factor of 6 to get clear water.

Hey Sean,

So its just green water rathe rthan brown or anything?

When was the last time you did any water changes or topped the pond up? ALso when was the last time you changed the UV bulb?

dont see how you can say my filter isnt up to the job when i didnt give any specific advice on the filter, just said its a good one and fairly large, has all the seperate chambers and gubbins inside.

water is just green. tool a sample of it and can see its green, tried the clear water stuff and although it did bring up a load of crap it didnt clear the water.

havent topped it up for weeks. only when we had some blistering sun and it dropped down an inch or so.

UV light hasnt been changed since new. onlt been running for 3months. is this the cause?

Hey Sean,

Is there a UV on the other filter box (not the 4-1)? If not then i doubt that the UV is big enough to cope with a mature pond that gets a bit of sunlight.

If there is a UV on the large filter box then what wattage is it?

No external UV light, im off to buy one this afternoon actually. Ive been thinking this for a while now.

I was also thinking of adding a second filter box of just fine media to aid the filtration. Good idea? cant have too much filtration surely?

my current filter box can handle up to 15,000L so im doing much less than that more like 6000L

I took out the Uv light on the 4-1 pump and as you say its very small. No where near enough.

If i include a large Uv light into my pond, what should i do about the water in its current state? Will the UV clear it eventually or should i do a 50% change to aid it?

A bigger UV will help but it can take time 2-6 weeks for it start working, and i personal wouldnt do a water change as the phosphates in the tap water can cause more problems, it could use a product like Green Away which would aid.