Pond Boss Forums MANAGING AN EXISTING POND Fertilization Green film after first time fertilizing

I fertilized my pond for the first time last Thursday with granule type fertilizer. I went to the pond today and have a green film on a third of the pond, and im sure if the wind changes direction it will follow. Do I need to worry about this film on the pond and will it possibly go away by itself? I'm sure its from the fertilizer due to this being the first time the film has shown up and it was just built in May. I plan on stocking in October and don't want to cause harm to the fish. Oh yeah, some of the green film has bubbles in it. Thanks for the help in advance.

Henry, the experts here (of which I am not!) generally recommend fertilization in the spring when the water temps hit the mid 60s. When the water gets hot, say mid 70s plus, most of the time fertilization is not advised.

If the film is a neon-green color, you may have blue-green algae which isn't good. If so, I'd wait until it dies back before stocking. Wouldn't add any more fertilizer, either.

But the experts might totally disagree with me, it wouldn't be the first time I got something wrong.

I think you will be ok, but you did not mention how much fertilizer you used and pond size and what your water visibility was before and after the treatment. To much fertilizer might influence more than you wanted. Where is your visibility now?

Tracy, visibility was about 24 inches before and now it's around 20 inches so it hasn't changed much. I used a cheap granule type fertilizer from the local co op which calls for 40 lbs per acre. My pond is a little less than half acre so i used 17 lbs in a bag and cut an X in it so it wouldn't touch the bottom. I feel like i applied the correct amount in the correct way, but maybe should've waited til the spring...I will just be happy if the ugly film goes away.

I'm curious, what were the fertilizer numbers on the mix you used? I ask, because that seems like an enormous amount of fertilizer to me. I use Pond Pro granular 10/52/4, and they only recommend about 5 lbs or so an acre. I actually stopped fertilizing about a month and a half ago since it seemed that all I was doing was feeding the FA.

Its 20-20-5 and called Magic fish pond fertilizer made by a fertilizer company in dothan, al. It may have been the excessive nitrogen that was the issue. I just checked out the pond and the green film is now almost non-exsistent.

Good deal. Glad it has gotten better for you!

Ok, so I went and checked the pond this morning and it almost looks like a bubbley oil slick on the entire surface. I sat and watched a while and see bubbles coming up from every where, slowly. We didn't have much wind yesterday and it hasn't rained in a couple weeks. This is starting to freak me out. Anybody have an idea?

What is your visibility ?
Are there fish in the pond ?
No more fertilizer this year.
Did you have the soil/water tested to see if you even need fertilizer?
Many ponds don't need any due to rich dirt/pond bottom.
That is to much N (first number) for me. Often 0 N is needed. Excess N often causes blue/green algae blooms. See this archive.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=96127#Post96127

I also think its probably due to excess nitrogen, thus all the bubbles. I had my water tested and was told i could benefit from lime and fertilizing. This first round of fertilizing was really just a trial and error run since I haven't stocked yet. Would you pull out the bag that has the remainder of fertilizer from the pond?

Visibility is still around 20"

If there are no fish I would just let it work through.

Lime alone often raises pH enough to allow the uptake of dissolved nutrient already in your pond, without additional fertilization.

The bubbles are likely trapped oxygen produced and or carbon dioxide respired from the BG algae bloom

Rainman makes a good point. That is why you need to know the situation first before adding fertilizer. If low alkalinity is the problem (limiting factor) then add ag lime. Don't follow with fertilizer unless needed. Anytime you remove a limiting factor the results may surprise you. If you have plenty of nutrients but low alkalinity and add lime often the plankton take of like crazy without fertilizer.

Thank y'all so much for your help. Its just so weird how it changes from day to day. I will be happy if its good to go when im ready to stock...and I hope we get some rain next week.

How quickly does ag lime typically start changing the PH? When do you see the full effect of it?

Some change is immediate but most happens over time. In my experience - every pond is different - a lime application lasts about 2 years with the max effect after about 1 yr. See the post above about being sure you know what the limiting factor/s on your pond are.