Pond Setup

[Vmw]

Well, we drained the pond due to green algae issues that we could not get under control. Looks like we’re going to try again. We have a filter, and a UV light. The water ph is 7.6. I think goldfish prefer 7.5‍I believe there are too many fish-4 or 5 would be plenty but my husband will not part with any.. after one week, it looks like it’s starting to turn green again. I know we need plants for inside the pond. Any other ideas to eliminate green algae? It’s not string algae.
Thanks.

 

[combatwombat]

What are you doing for mechanical and biological filtration?

Even with an amazing filter, you either need plants to consume nitrates and outcompete algae or massive, regular water changes that can be stressful to your fish.

A UV light just hides the problem until it’s too big for the light to fix.

Your PH is fine. PH hardly matters as long as it’s stable. And your pond looks like it’s big enough to support a lot more than 5 goldfish, so that’s not really concerning either.

 

[BKHpondcritters]

By draining the pond & starting over you will inevitably experience 'new pond syndrome' which unfortunately usually means an algae bloom while the pond/water/system cycles.

Yes. You do need plants. Lots & lots of plants. Right now you don't have any other plant to use up the nitrates being produced so nature is providing you with one - that algae is probably keeping your water safe for those fish.

And I agree with combatwombat - your ph is fine. Keep it stable (monitoring your kh will aid here) and the fish will adjust. It's wide ph swings that they don't tolerate well.

 

[Vmw]

What are you doing for mechanical and biological filtration?

Even with an amazing filter, you either need plants to consume nitrates and outcompete algae or massive, regular water changes that can be stressful to your fish.

A UV light just hides the problem until it’s too big for the light to fix.

Your PH is fine. PH hardly matters as long as it’s stable. And your pond looks like it’s big enough to support a lot more than 5 goldfish, so that’s not really concerning either.

We had water lilys last year which died, I do intend to buy more aquatic plants. We started with 12 tiny goldfish 4 years ago, now there are 30. Seems to be a happy place for goldfish.

 

[Mmathis]

It’s hard to kill water lilies — that’s odd. Just curious, but how did you have them planted.

Also, water lilies, while good at shading the pond, are not the best for removing nitrates. For this you need plants that have roots in direct contact with the water.

It sounds like there might be more than one problem here, as others have commented, so maybe let’s start at the beginning:

• How big is your pond
• how long has it been up and running (well, before you drained and cleaned it, that is)
• what kind of filter do you have
• is the pond in full sunlight
• how much do you understand about the nitrogen cycle, and how it interacts with the pond

 

[Vmw]

The ponds volume is approximately 1900 US gallons. It’s been in existence for 46 years. I inherited it from my parents. I can only remember once when they had it that the water wasn’t green. I do not recall them ever having plants in it. There was a fountain in the back, left corner of the courtyard where the water would recirculate thru a swimming pool filter under the house and come up thru the fountain and under a dry creek under the sidewalk. It was a nice feature, however those filters no longer work so the drain in the pond is covered with the liner. We have a small filter/pump because our larger one seemed to cause the water to circulate too quickly thru the UV light. This pond is in full sun for about 4 hours a day. I have purchased water lettuce and water hyacinths so I’m hoping this helps. It was not water lilies that died, they were water hyacinths. I know very little about the nitrogen cycle except that the fish excrement is a big cause of the proliferation of green algae growth. One thing about it, the goldfish thrive in it..

 

[poconojoe]

Nice pond!

 

[poconojoe]

If you live in an area where the winters are cold, your water will probably get green in the spring due to all the fish waste. The water temperature needs to be 55F for the beneficial bacteria to grow. Mine didn't totally clear up until mid June. I'm in zone 6b. But I do have way too many fish.

In the Springtime we all need to have some patience. Once the beneficial bacteria kicks in and your plants start growing, it should clear up, even if it was pea soup green.

Of course, your filtration needs to be up for the task.

 

[Vmw]

We are in 8a-can get into the teens in the Winter but not frequently.

 

[GBBUDD]

Filters are key to achieving clear water.
Overfeeding must be avoided to prevent algae blooms.
Look at every pellet of food as a hamburger. When's the last time you ate 10. 20. 30 hamburgers in a day but that's often what we give during feedings
Your uv you seem to be using on the front end of filtration it at best is the tail end where it can be beneficial.
There's a lot of information on this site . Mostly about a natural approach with bog filters but several regs use filter mats and canister filters as well