I have been reading through a lot of the posts about green water, although my water is green right now, it has not been clear since we did a complete overhaul of the pond 3 years ago to remove iris which had taken over. The iris had grown to about 1/3 of the pond and they were planted in the middle so they were restricting the fish from swimming from one side to the other. Anyway, I believe those iris were keeping the water nice and clean and I have not been able to get it clear ever since. Following is what I've done and some questions. Thanks!

1. Pond specifics: pond is 8 feet by 12 feet rectangle, above-ground, 18 inches deep.


2. Plants/Shade: Pond is in full sun. About 1/4 of the pond has plant cover (maybe less than 1/4 as they are still growing) and I have covered half the pond with shade cloth.

3. Filter/pump - I'm using a Tetra OFX 2000 submersed pump and a Tetra ClearChoice PF2 external biofilter. I put in the filter this Spring about 2 months ago. I was using other in pond filters before that, upgraded to this. Specs on the pump say the max gph = 2000 gph and the filter says it handles 750 gph. Hoses are 3/4 inch I think. Maybe 1 inch.

4. Fish: 3 koi, one is about 18 inches, the other two about 12 inches. Goldfish, about 30, they multiplied. When we cleaned the pond 3 years ago, we only had 7 fish, 3 koi and 4 goldfish/shubunkins.

For three years, the water has been murky. The bottom of the pond does not have a sludge buildup, it feels clean, so what is in the water is suspended, which is why I got the filter. Now the murkiness is combined with green water. No string algae but just green. Last year I tried: water hyacinth for shade, a UV filter and underwater oxygenators with no results. I no longer have the UV filter as it wasn't doing anything for me.

Some of the murkiness could be dirt, the large koi likes to knock over my plants and dirt spills out but i think this only happened when I first put the plants out, I have since filled the pots with rock instead of dirt but I think there may be dirt in the pond, though I wouldn't think it would be causing so much murkiness? This was only one or two pots that were not very big.

When I put the external filter in this year, it sits at the edge of the pond so the pump has to pump water up about 4 feet to the top of the filter and then the water falls down on the filter pads, through the plastic media and then out a spout on the bottom back into the pond. When I first put this all together and turned it on, the water gushed back into the pond. I anticipated clear water soon. Sigh. It has now been eight weeks. The water no longer gushes, it trickles, I'd say it's at half the flow now. For the size pond, it doesn't seem to be enough force to do any good.

I clean the filter pads regularly but don't touch the plastic media. This weekend I took everything apart, all the hoses, checked the pump for problems. Everything was fine, no clogs. I even finally dug down into the plastic media to see if there was a clog at the bottom of the filter preventing water flow and found nothing, all clear.

QUESTIONS:

1. I have read it takes 6 weeks to build up the bacteria needed to start filtering? How do I know when that is happening? Could that be the problem? The bacteria hasn't built up yet?

2. Water coming out of the filter is green not clear, is that right?

3. It was hot this weekend and the fish seemed to be sucking up at the top, does that mean they aren't getting enough oxygen? It cools down here at night so they were fine this morning. One fish was up in one of the plants yesterday and got stuck almost out of the water. Do I have too many fish? I know 18 inches is not very deep, I didn't build the pond.

4. With a 2000 gph pump and a 750 gph filter, I'm wondering if I need a different filter? It doesn't make sense to me. It seems that if my pump is that strong, and water is only trickling out, I need a stronger pump? What am I missing?

5. Any other advice? Though now I feel the pond is shaded well but it is still very green. I have shade cloth still covering half the pond and plants on the other end.

Any help is much appreciated, thanks!