Debris Stuck to Bottom of Fiberglass Shell

[Steveareno]

I have a fiberglass Koi pond. I haven’t cleaned the bottom in 4 years. (It’s a long story, involving health issues.) I drained the pond and tried to clean off the accumulated debris on the pond floor. Most came off easily. But a significant portion of the debris was very firmly stuck to the pond bottom. I tried to remove the debris with a very stiff brush, which did loosen a little bit of the debris. I also used CLR. I want to be careful not to injure the gel coat. I do not have Koi or any plants living in my pond, and never had. I plan on adding plants and Koi in the future. Can anyone suggest how I might remove the debris?

 

[Meyer Jordan]

Can you post a photo of this "debris". It may be part of the biofilm layer.

 

[Steveareno]

 

[Steveareno]

Hi Jerod,
Thanks for your reply. I'm sorry the pictures are not very good. The debris have the surface consistency of sandpaper to the touch. The debris are very firmly attached to the fiberglass shell.

 

[Meyer Jordan]

Are you positive that this is debris or is it a degradation of the surface of the fiberglass?
If it is firmly attached it is not debris but part of the biofilm.

 

[Steveareno]

Hi Meyer,
Thanks again for your response. The debris are firmly attached to the bottom of the pond. They appear to be "blisters" rising above the surface of the fiberglass. They have the surface consistency of sandpaper. It might be a degradation of the fiberglass, I just don't know as I'm ignorant on fiberglass. It's as if someone dropped dabs of glue on the surface and then sprinkled sand onto the glue giving it a rough consistency.

 

[Meyer Jordan]

The coating on fiberglass will degrade over time due to UV radiation and bacterial action. Once the coating is compromised bacterial action will begin to degrade the fiberglass itself, This is common in underground storage tanks, It would probably be many years before this degradation would progress to the point of causing a leak.
Recoating is an option with any of the several Pond coatings on the market. This would be your only option, other than relining or replacing the pond, if the aesthetics are that important. Otherwise, leave it be. It should eventually be disguised by algae growth anyway.

 

[Steveareno]

The coating on fiberglass will degrade over time due to UV radiation and bacterial action. Once the coating is compromised bacterial action will begin to degrade the fiberglass itself, This is common in underground storage tanks, It would probably be many years before this degradation would progress to the point of causing a leak.
Recoating is an option with any of the several Pond coatings on the market. This would be your only option, other than relining or replacing the pond, if the aesthetics are that important. Otherwise, leave it be. It should eventually be disguised by algae growth anyway.

Thank you very much Meyer.

 

[Meyer Jordan]

Sorry that I could not come up with a more pleasant response.

 

[Steveareno]

Better to know the straight truth than getting a lot of stupid suggestions like, "Have you tried 409 or Windex?" Thanks again.

 

[Steveareno]

Sorry that I could not come up with a more pleasant response.

I just realized hat I have the same debris stuck to my drain cover. The drain cover is PLASTIC. Does this change your diagnosis?

 

[Meyer Jordan]

I just realized hat I have the same debris stuck to my drain cover. The drain cover is PLASTIC. Does this change your diagnosis?

Not necessarily.
Is this a constructed (on-site) pond or is this a large pre-formed fiberglass basin or other.

 

[Ruben Miranda]

Hi
It could be calcium deposits , once it takes hold it could be very difficult to remove.
Myself if it is not leaking and once water is it and not very noticable with plants in it and a few rocks. I would leave it be as scraping at it could cause even more damage.
I would also say if you are going to have fish and plants I would not use strong chemicals like that.
Because any residue could harm your fish and plants and the build up of the beneficial bacteria.
Ruben

 

[sissy]

koi will get to big for your pond stick with a fantail or 2

 

[Steveareno]

Not necessarily.
Is this a constructed (on-site) pond or is this a large pre-formed fiberglass basin or other.

This is a pre-formed 350 gallon fiberglass basin. Thanks, Steveareno