meitzler said:
Think of a consumer report equivalent for skimmers. One could have a large tank feed "x" number of skimmers in small separate sumps, thus they would all have the same water source. ................................
That is the only way you have any chance of making a comparison, but even then it is all too easy to skew the results.
The water in the tank should not be hooked up to a reef or fish tank. Too many potential variables in skimable waste load from test to test. I would suggest adding an exact amount of easily skimmed product to the tank water for each test and then compare skimmer performance.
We all know how easy it is to reduce or increase the skimmer performance. Stick your hand in the water and it stops skimming. Add a product like SeaChem's Reef Plus and the skimmer over flows with skimmate. Also, for the test to be of any value all variables need to be measured and equalized as much as possible.
The actual water throughput would need to be the same. Skimmer volumes would need to equalized by some formula. We all know a skimmer with a larger volume will pull out more skimmate, all things being equal. To compare a 25 gallon Bubble King to a 10 gallon ER is a waste of time other wise. I wouldn't be surprised if we found some unusual results, like....two small ER skimmer running in parallel or series, out performed a single larger skimmer of equal volume.
As an example: If we are striving for low nutrient conditions in a tank. You would want a skimmer to give the highest capture ratio of waste throughput. Simply skimming at 50% efficiency, and capturing the largest particles, and returning a large portion of the waste back into the system and could make it more difficult to capture on the next pass.
In a WWTP -waste water treatment plant, a frequent problem is capture of settled sludge. A lot of waste concentrating equipment,ie; centrifuges and belt presses, only scalp and get the largest particles capturing 80%; allowing the fines to be recycled back into the WWTP. This can quickly over load a plant production and shut a facility down. It is imperative to select and operate equipment so it capture 95% plus.
My point is that if you are striving for low nutrients a skimmer with a higher capture ratio on the first pass may have some strong pluses. This thinking leans toward a lot of air and low agitation, as frequently mentioned.
It isn't easy to make true comparisons with out having a good test proceedure.
All the recommended skimmer performance and design ratios should only be a starting point. I am sure new skimmer concepts will change our thinking, and what has been used to derive them for a tall air skimmer will not always apply.
Adding a measured volume of Reef Plus to the tank during the test and then measuring skimmate volume and concentration for each skimmer would need to be done. In this manner you could set up perfomance and test parameters for any skimmer and they would not need to be run side by side. As I stated before you also need the actual measured flow rates of feed and recirculation, and not simply what the pump rating is at zero head.
I get a kick out of Bubble King's claims of very low power consumption for their pumps. What they don't tell you is that they are adding such large volumes of air into the pump that is it is only pumping foam. The lower power consumption has little to do with the pump's efficiency. The same reduction in power consumption happens with any pump when you make it into more of an air fan than a liquid pump, by putting an efficient air venturi on the inlet and adding a large quantity of air it becomes part fan and part pump. That is not to say they don't make a good product.....but it is a little high in price / performance ratio for me. Sorry for rambling.....
Majoreef are you still using the airstone? I see where you gave another reefer a compressor and air stones. Didn't you state somewhere that you wanted to add a recirculation pump to your system? As I comment to you earlier I'm interested in your long term findings on going back to the original air skimmer concept.
