Interesting article--HOB skimmers better?

I read an article in Aquarium Fish International yesterday about protein skimming. The author made a very interesting point about the most efficient way to use a protein skimmer. He said the best way to use a skimmer was to put it in a place where it was getting water from the surface (where most of the yucky stuff resides) and then returning it directly to the aquarium.

Those skimmers in a sump have their processed water constantly mixed with unprocessed water from the aquarium, with the return pump returning only partially skimmed water.

So I guess the argument is that HOB skimmers have their intake closer to the surface. But doesn't aquarium water have a mix of processed and non-processed water too just like a sump--just on a much larger level? Anyway, as I am looking at an upgrade for my skimmer it made for interesting reading. Maybe if I could find a skimmer that would send the processed water into the first baffle of the sump?

 

I tend to agree that a skimmer that is fed directly with untreated water that is skimmed off of the surface will tend to have more "gunk" to work with hence it's increased skimmate output.

That is not to say that a skimmer post-treament (filter socks, media reacter, etc) will not work - it's just that it does not have the same raw materials to produce skimmate.

But I do agree that it is always best to give the skimmer and the fuge compartment the dirtiest, most untreated water possible.

 

Sort of true sort of not true.... in the end... it does not really matter.

In any filtration sytem, you want a once through inline design. All dirty water goes in one end, all clean water comes out the other. That is pretty impossible in our sytems.

You want surface water because that is where the hydrophobic disolved organics will go due to the air/water interface. Overflows skim off the surface of the water. But that is also in a sytem where there is not much movement... most folks try to keep the surface agitated and the tank well mixed with powerheads.

You would want the skimmer to process the water and then discharge to a clean tank.... or at least have the discharge as far away from the skimmer inlet as possible. So a HOB or a sump would return to the bottom of the tank in the furthest corner away from the HOB in the top opposite corner or overflow. Yet nobody has that setup and again with as much movement of water as we have in reef tanks it would not really matter much.

Very few HOB skimmers skim off the surface.... the better ones out now have seperate overflow boxes they draw from that skim surface water which is a much better design.

HOB skimmers discharge right next to their inlet.... so not exactly seperated much.

When designing a sump, the best way to do it is to put the skimmer inlet next to the drain coming from the tank. Mine was flowing right into the intake. I knew I was taking a suction of nothing but tank water. But I had a elbow on the end of my Herbie which was easy... dumping into a filter sock would be much harder. Or anything else really that does not direct flow to the skimmer.

Next, if you have bubble traps, none of that surface skim will make it back to the tank. All the surface water dumped into the sump is trapped by the baffles in the skimmer section. I regularly had a surface skim in my skimmer section trapped by the baffle.

As long as that is done, then the discharge does not really matter. If you have a sock or some other overflow that just infuses into the skimmer section, then the best that can be done is to have the skimmer discharge next to the bubble trap to go to the return.

Last would be not to send return water across the surface of the tank. I had my returns going down the back of the tank to provide clean flow through my rock work... at least that minimizes fresh clean water going directly back to the overflow. Also only move as much water as the skimmer needs. Too much and it wastes power, too little and you recirc water in the compartment and don't process as much

Having said all that..... it does not really matter. Skimmers process many times an hour. Powerheads keep the tank thoughougly mixed. The return pumps keeps water moving through the sump. Then there are the whole group of RECIRC skimmers that work quite well.

At the end of the day, skimmers remove what hyrophobic DOCs that are there. We have very clean water, and our tanks do fine. Very few HOB skimmers can compete with good in sump skimmers.

 

So which ones are those? Who makes HOB models with seperate overflows like you mentioned? thanks.

 

My octopus BH-100F HOB's inlet is a surface skimmer.

At one time I had a PH pointing to push the return water away from the intake. I eventually quit caring about that as it made it hard to achieve optimal flow patterns for my LPS and I haven't seen any difference...