How green is green? Cant see fish or just not crystal clear? Yellowish green. Usually worse in mid-late afternoon under hot sun. Water clear to one third down 6 ft pond at night. Not crystal clear, but can see fish clearly when they swin near the surface. HAs carpet algae fully covered the pond walls? Yes, healthy dark green except where epoxy coating is peeling. How much filter materials do you have in the filter? 1st chamber of filter brush, 2nd chamber of Kaldanes K1, 3rd and 4th chambers of Japanese mat, last chamber of oyster shells and bio balls. All the filter chambers are aerated. I also have a waterfall with 2 7ft x 3ft glass panels coated with an experimental Japanese photocatalyst oxidation coating that cleans organic matter under sunlight and night UV light from a thin film of water and a 7ft by 5 ft concrete wall studded with broken bacteria house and marble chips over which a thin film of water cascades. Both the glass panels and studded wall creates turbulent white water and foam collects at the bottom of that section which houses my lotus and water lily vegetation filter. Water spills from that section into the main pond. How much aeration do you have in pond and filter. I am running 2 units of Hiblow 120 through 3 uniring airlifts built around 3 bottom drains and the filter chambers. The bakki shower cascades over 3 PVC columns with holes in the inside 8 in pipe with a outside 10in pipe with holes at the top and bottom. Only the middle part of the outer pipe have no holes to prevent splashing -- seems to work well with thorough mixing of white water as they cascade over lava rocks/experimental porous ceramic bricks and bioballs. Air is sucked in from the top of the columns and also in between the pipes and through the holes in the inner pipe and escapes through the bottom holes. The bakki trough also houses another vegetation filter with arrow plants and Japanese yam plants, which spills over a stream lined with river rocks before falling into the main pond. I am also experimenting with some flat porous lava rock tiles on this 6ft x 2.5 ft stream to create more turbulent white water to improve aeration. I'm now toying with getting a 80 cm Japanese suisha water wheel for this stream to improve aeration when I visit Japan later this year.

I remember i yr post, your bakki is somewhat enclosed in a plexiglass? If so, I believe gaseous exchange is not at optimum hence the bakki is not functioning at its potential. Maybe you are right here. Will consider changing to bakki tray system after figuring out the correct pond turnover rate and the water still fails to clear up.

Assuming that you have been hardworking geeting rid of the solid waste,this is what I think. I religiously empty the 1st and 2nd chamber every morning -- 10% water change is about 8 tons of water which blew up my water bill! Plus weekly cleaning of the brushes and filter chambers 2 at a time. 1st we need good gaseous exchange to rid of ammonia. then lots of aerobic bacteria to eat up the nitrite and nitrate. This we need adequate filter material to house them and lots of aeration to help them work. Then a nice thick coat of carpet algae on our pond walls to eat up whatever is missed by the bacteria. As you can see, I've been quite busy experimenting with all sorts of methods to improve the water quality. I also have 5 UV lights -- 3 for the clean water chamber and 2 for glass waterfall panels.

My renovated pond has been running for 2 months and still has a slight yellowish tinge. I have 46 tons and running 2 filter lines: 2X 12k liter pumps up a shower and 1X 12k pump direct to pond. I have a 20 watt UV. I also have 2 uni-rings powered by 100 watt airpump each. Also have 2 X 80watts for the filter. My pond is 20% shaded.
I intend to raise the height in between the trays of my shower as the current height is not allowing efficient gaseous exchange.
Also, CArpet algae is not growing well in my epoxy-coated pond. and they are a big nitrate consumer. I just have to wait a little longer and maybe you will have to as well With a total pump output of 36 tons per hour, your pond turnover is once every 1.27 hours. My contractor recommended 3 Tsurumi 40PU pumps (1 for the waterfall and 2 for the water circulation jets) with a measly combined output of 25.5 tons per hour and a pond turnover of once every 3.25 hours! After doing all I could to improve the water (short of shading the pond with an expensive pergola that the sub-contractor is hoping for and my missus is dead against), I have realised to my dismay that I might have been shortchanged by the pond contractor who may just be doing a bad job on basic technical stuff such as right sizing of pumps! The other thing that bothers me is the water in the up down filter chambers are at least 4 inches above the brushes and 12 inches above the Jap filter mats. The Jap filter mats have gaps of 6 inches between the chamber walls, and I do wonder if dirty water is basically channelling though all these gaps into the pond. The sub-contractor keeps saying that the chamber design is fine and water must stay long enough in the filter chambers for the nitrifying bacteria to work and that I should stop feeding and move out all the fishes save for 6 only and I should spend another RM50K on a pergola! Duh -- why didn't he suggest keeping the pond empty??? After 5 months of tinkering around, is the culprit simply the lousy contractors getting the pump capacity wrong? They have screwed up often enough with peeling water proof layers, wrong electrical wiring which caused a small fire, killing show winners etc... Is it possible they might have screwed up the pond turnover rate too? Jeff