Oily film

[Oblio]

I just noticed an oily film while doing a WC and BGA cleanup.

Only recent changes within the past WC last week was the addition of two new Pothos and some aphids by flushing them off a Basil cutting. It appears there are a few aphid larvae but certainly not enough to spike ammonia give the tank size.

Tank is 125 gal, understocked, fish behavior is normal.

Temp 74 F, pH/NH4/NO3/NO4 == 6.8/0/0/5

Do I need to skim the film or will it dissipate, or just not worry?

 

[connorlindeman]

Seems like you have a oil slick. What are you feeding the fish? Oily film can be caused by low quality food or over feeding.
It can also be caused by putting your hands in the tank.(oil on your hands)
Aerosol cooking spray also causes that.
Excess fish waste
Or maybe a fish died. Have you counted the fish lately?

 

[Colin_T]

If you don't have a lot of aeration or surface turbulence, then you can get an oily film on the surface of the water. It is usually associated with protein from fish food but can also appear when algae or blue green algae is growing around the surface.

You can sometimes blot it up with a dry paper towel. Just lay it on the surface and then lift it up and remove the paper towel. Water changes can help remove it as well.

 

[Oblio]

Seems like you have a oil slick. What are you feeding the fish? Oily film can be caused by low quality food or over feeding.
It can also be caused by putting your hands in the tank.(oil on your hands)
Aerosol cooking spray also causes that.
Excess fish waste
Or maybe a fish died. Have you counted the fish lately?

All fish are fine, no change in feeding amt or schedule - Hakari wafers, Bugbites pellets, and Omega One color flakes. Occasional (1-2x/week) frozen treats, Daphnia, Brine Shrimp, Bloodworms.
There has been a bit more BGA since I put a Aqua-garden hydroponic unit next to the tank - BGA loves the light spillover. Perhaps it is that as Colin suggested or Basil oil from scraping the aphids off the leaves.

 

[Oblio]

If you don't have a lot of aeration or surface turbulence, then you can get an oily film on the surface of the water.

I have decent turbulence with AC 110, at least on the right side of the tank, but there has been no change from when there was no slick.
I did just notice that there is a small patch of BGA at the waterline, near the outflow. Normally this is not present but since adding the Aero garden, there has been more light in this area.

 

[Back in the fold]

@connorlindeman mentioned aerosols. I go to great lengths to avoid those as aerosolized things are more easily absorbed at the water surface / atmosphere interface. (Whew ! That was tough. Hope I used all those big words right)

 

[Oblio]

@connorlindeman mentioned aerosols. I go to great lengths to avoid those as aerosolized things are more easily absorbed at the water surface / atmosphere interface. (Whew ! That was tough. Hope I used all those big words right)

We generally don't use aerosols, but a month ago I did open the filter lid to allow the bamboo a place to grow. It just seems it is something recently changed that is causing the slick.