Pond Over-Fertilized

[John Mulhausen]

I have a 2000 gallon back yard pond with several plants and a few Tilapia. I have an external filter and also an aeration fountain. I decided to fertilize the pond with 15-30-15 granular fertilizer from Home Depot for the plants and produce more algae for the fish to eat. Before fertilizing the water quality was near perfect. I put about one cup of the fertilizer in a cloth sack and dropped it in the water for 4 hours then took it out with about half a cup remaining. After fertilizing the water quality reading went way too high for nitrite, ammonia and phosphate. Many experts suggest fertilizer but in general, wouldn't that increase the three bad chemicals way too high? Confused. Has anyone else had this problem? Now I'm doing a water change to get things within range again.

 

[Meyer Jordan]

Fertilizer is often used to kick start the food chain in earthen bottom ponds which can support a wider diversity of micro-organisms than a liner pond. Even then commercial fertilizer is never used, but animal manure.
If you have a liner pond, any fertilizing is a big mistake.

 

[John Mulhausen]

Fertilizer is often used to kick start the food chain in earthen bottom ponds which can support a wider diversity of micro-organisms than a liner pond. Even then commercial fertilizer is never used, but animal manure.
If you have a liner pond, any fertilizing is a big mistake.

Thanks for the advice. The water exchanges are getting things back down. My guess is about 1/3 to 1/2 cup desolved into the water. So far the fish don't look stressed. Hope I caught it in time. I did look all over the internet before I fertilized and found several sources recommending fertilizer. Like you said, they must have been only talking about large soil bottom ponds and I didn't see any warnings for smaller lined ponds. I obviously put in way too much. Once I get things back to normal, do you think it is safe to use any fertilizer spikes in my potted plants?

 

[Meyer Jordan]

Thanks for the advice. The water exchanges are getting things back down. My guess is about 1/3 to 1/2 cup desolved into the water. So far the fish don't look stressed. Hope I caught it in time. I did look all over the internet before I fertilized and found several sources recommending fertilizer. Like you said, they must have been only talking about large soil bottom ponds and I didn't see any warnings for smaller lined ponds. I obviously put in way too much. Once I get things back to normal, do you think it is safe to use any fertilizer spikes in my potted plants?

Really depends on your pond. Number of fish, hours of sunlight, volume (gallons) of pond.
In most ponds, ample nutrients are supplied by the presence of fish to meet the needs of aquatic plants. Plant spikes or tabs can be used sparingly as they too will release a certain amount of nutrients into the water.

 

[pecan]

Thanks for the advice. The water exchanges are getting things back down. My guess is about 1/3 to 1/2 cup desolved into the water. So far the fish don't look stressed. Hope I caught it in time. I did look all over the internet before I fertilized and found several sources recommending fertilizer. Like you said, they must have been only talking about large soil bottom ponds and I didn't see any warnings for smaller lined ponds. I obviously put in way too much. Once I get things back to normal, do you think it is safe to use any fertilizer spikes in my potted plants?

I use aquatic fert tabs in potted pond plants, like lily's and a Cypress tree I have in a pot in the bog. I would only use those specific for in pond use and sparingly and only in pots.

I bought these last time from Amazon.
https://www.amazon.com/AgSafe-Aquat...09115&sr=8-2&keywords=aquatic+fertilizer+tabs

My lilies get about 3 tabs per pot per month from May - August
My Cypress gets about 3 tabs in the pot every couple months from April - August

 

[John Mulhausen]

I use aquatic fert tabs in potted pond plants, like lily's and a Cypress tree I have in a pot in the bog. I would only use those specific for in pond use and sparingly and only in pots.

I bought these last time from Amazon.
https://www.amazon.com/AgSafe-Aquat...09115&sr=8-2&keywords=aquatic+fertilizer+tabs

My lilies get about 3 tabs per pot per month from May - August
My Cypress gets about 3 tabs in the pot every couple months from April - August

Thanks. I'll certainly check into that.

 

[MitchM]

Fertilizing any aquatic environment is risky, imo.
You really need to track your water parameters and have a solid reason to add fertilizer in the first place.
Algae will be more than happy to start growing in the presence of excess nutrients and lock those excess nutrients in place until you remove the algae yourself.

 

[crsublette]

@John Mulhausen , those Tomato spikes are also very commonly used to help the more finicky pond plants.