protein skimmer for blackwater tank

[tongolino10]

from some reading online, I discovered that there has been talk about freshwater protein skimmers.

do they work differently from those used in saltwater tanks?

I noticed some talk about them being more effective in alkaline/hard water systems.

therefore, I'm wondering if they would still be effective in blackwater systems, which typically have a low pH?

also, my understanding is that they won't remove tannins from the water. do correct me if I am wrong though

 

[duanes]

I have have used DIY models on fresh water tanks, and ponds.
They work almost the same, except it takes more agitation in low density fresh water, than high density salt water, so in my experience a stronger water pump is needed to create a break in the air/water interface.
Fractionation occurs naturally in fresh water, from wave action, the foam below water falls, etc

Above left the foam produced on my tilapia pond, although on the counter current one I built (middle shot,) produced slightly more wet foam, right the bag of waste water foam
Below the venturi tube needed for a counter current version., and waste collection bag

Below a video of one I built working on a Koi pond.
koi pond fractionation
I also did weight comparisons in the lab, of desiccated fractionation waste compared to tank water.

In comparison desiccated dry weight of fractionated waste averaged 8 to 10 times heavier the filtered tank water.