Does anyone know what feed pump to use for an H&S A150 skimmer?

[OceanGirl]

Hi there everyone,

I'm getting really excited now!! Jeff from Lifereef just called me about the custom sump/refugium I'm going to have made, and I'm hoping you fine folks here on RS can help me out. I have an H&S A150 protein skimmer that is going to be run in-sump due to space restrictions within my stand. I was wondering if anyone knows what a good feed pump would be for this skimmer, as they really don't say on the H&S website. If anyone could help me out on this I'd really appreciate it! You guys have been great so far!

[sasquatch]

heres some light reading for you that should explain a bit, when youve arrived at the gph you need let us know and we can debate what a good pump is.Steve PS! hit the link at the bottom for the chart and whole article

1. Water Flow Rate Through the Skimmer:

For optimum skimming using a counter current design (or actually any other design for that matter), the water in your tank should not flow through the skimmer any more than two times per day. For venturi's, downdraft's, and beckett's, this requirement is almost a virtual impossibility as the pumps need to pump the huge amounts of water to yield a sufficient quantity of air to skim. This may seem strange and even shocking to many people as they are used to the "Tim Taylor" - type skimmers (more power! Oh Oh OH OH oh!) that push huge volumes of water through a skimmer every hour. Many people believe that to skim more effectively and efficiently, you have to increase the water flow through their skimmer as the air bubbles will contact the air bubbles more times per hour. This is NOT the case. The water running through the skimmer is not the limiting factor when it comes to nutrient export. It's the amount of AIR that contacts each "drop" of water that is the limiting factor to how much a skimmer pulls out of the water column. Some organics require up to 2 full minutes of contact time with air bubbles in a skimmer before they are removed via foam fractioning. Thus the need for a slow water flow through the skimmer is crucial for proper design and function.

According to Escobal, the following chart should be used to determine the flow rate for water through the skimmer (assuming a 2x per day turnover rate):

Find the net gallons of water contained in your system on the above chart on the X-Axis and follow that value vertically up the chart until you contact the green line. At that point, follow the line over to the left to the Y-axis. This is the flowrate that should flow through your skimmer for optimum skimming. This particular flow rate will run all of your tank water through the skimmer two times each day.

For example, let's say you have 100 gallons of water in your reeftank and you want to find out how many gallons per hour you should flow water through your counter current skimmer for optimum skimming. Find 100 gallons on the X-axis, follow the line on the chart vertically until you hit the green line. Now follow that over to the Y-axis to find out how much water should be run through your skimmer every hour. In this case it is 75 gph. Thus, for your counter current skimmer the tank water should not flow through the skimmer any faster or any slower than 75 gph. Pretty straight forward.

Using the above example for a moment, this should then raise another question: I'm flowing 75 gph through my skimmer. According to that, I should be running all of my tank water through the skimmer every 1.333 hours (100 gal/75 gal/hr) and not every 12 hours. Contrary to popular thought, this is not the case. Every time you run water through the skimmer, it dumps the water back into the tank of "unskimmed" water thereby diluting it. As water is continually pulled through the skimmer, it will then pull in "skimmed" and "unskimmed" water. As more "skimmed" water is pumped back into the tank, more and more already "skimmed" water will flow back through the skimmer. According to Escobal, the following equation is used to calculate when 99.99% of the water has flowed through the skimmer:

T = 9.2 (G/F)

Skimmer Design 101

[OceanGirl]

Hey, thanks, sasquatch! That's some interesting info there! Thanks for taking the time to send it all to me! Although when it comes to math I'm a total moron and after reading for a while I may start seeing things like this LOL! Just now I did get an e-mail from Eric at Fins Reef and he said 225-250 gph would be the flow rate. Just a thought--what do you think about the Eheim Compact pumps? Ooops-almost forgot--my skimmer is a recirculating type, and I noticed the article you sent me seemed mostly to be about counter-current skimmers. Don't know if that makes a difference.

[mps9506]

You will be very happy with the Eheim pump. some folks also divert some flow from their overflow drains into the recirc skimmers, but it is difficult to determine how much flow they are getting like that, and can be subject to surging.

[OceanGirl]

Thanks so much!