Dirty liner....

[nads32]

Help.....new build pond last year, new pump, filter plus Velda Itronic fitted, crystal clear water but pond liner and paddle stones under waterfall go green/brown within a week? Any advice gratefully received....

 

[MitchM]

Welcome!

Please tell us a little more about your pond. Size, population of fish and plants, what type of filter, what the flow from your pump is.
Post a picture as well.
Also, that Velda I-Tronic should not be used. It is an ionizer that releases copper into your pond.
Please read the following article: https://www.gardenpondforum.com/threads/are-pond-ionizers-safe-you-be-the-judge.16720/

 

[nads32]

Hi, Filter is a Laguna PF8000 pressure flow with uv, Verity Nova 200 Pump, pond is approx 3.5 mtrs long/1.8 mtrs wide and 0.5 mtrs deep, approx 3000litres. have just removed plants as black algae build up, have approx 60 small ( 1 inch) goldfish and 6 2-3inch goldfish. I have attached a pic for you!

 

[MitchM]

The algae that is covering all your submerged surfaces is keeping your water healthy for the fish.
I would say that your pond is overstocked with fish as well.
Have you performed any water tests?

 

[nads32]

all tests done fall in line with the recomended levels - nitrate / ph /amonia? always had this level of fish but never had this much of an issue........

 

[sissy]

the more you feed fish the more they will not eat all the good stuff in the pond that you seem to dislike .But like said it keeps fish healthy

 

[MitchM]

The sudden apperance of algae is the indication that your nutrient levels are getting out of hand and the set up can't be very old if your goldfish are only 1 inch long.

 

[nads32]

The sudden apperance of algae is the indication that your nutrient levels are getting out of hand and the set up can't be very old if your goldfish are only 1 inch long.

Pond was built end of august last year

 

[MitchM]

When it was built, when it was stocked, how it was cycled, what and how much the fish are fed, any fish deaths/additions along the way are important pieces of information.
What have the actual test numbers been? "Within recommended levels" doesn't help much. At some point you had elevated phosphate, ammonia and nitrate levels, otherwise the algae wouldn't be feeding and growing as you have now noticed. Did you perform regular water tests? If so, then you would have noticed elevated nutrient levels shortly before the algae appeared. The ionizer will only complicate matters because it is hazardous to your fish.

These are all things to be considered when diagnosing a change in your pond's appearance and water quality.
66 fish in a 3000l/800 gallon pond is overstocking, imo, and you are now seeing the results.

.

 

[nads32]

thank you for your info, its much appreciated. What fish numbers would you recommend for a pond this size?

 

[MitchM]

Because of the shape of your pond, It looks like the actual volume is closer to 1500L/400g. I would limit the number of fish to 10 goldfish if you want to avoid maintenance headaches in the future.

 

[Smaug]

What is your actual ammonia reading,nitrates and nitrites too?

 

[nads32]

PH 8
Amonia 0
Nitrate 0.3

 

[Smaug]

Looks like good numbers to me. Liner going green brown is fine,it's the stuff you want.