I am buying a Zakki Sieve to add to my Ultima II 4000 for our pond that is approximately 2500 gallons. We are upgrading our 1/12 HP old pump to something bigger at the same time. I am trying to figure out what I need as a pump. I am leaning towards the PerformancePro Artesian2 series. They seem to have a good reputation and the numbers (head and flow vs power and price) seem to be pretty good. I think I need either the 1/3 or 1/2 HP pump, but am struggling with figuring out which one.
The Ultima II 4000 wants an "optimal" 4000 GPH. Currently we have about 1000 GPH (according to my filling a bucket test), and I think 4000 GPH would work well for our pond. Here is a rough schematic of the plumbing I have planned:
I made a spreadsheet of all the pipe lengths and fittings. For the flex PVC I multiplied it by 1.2, which seems a commonly accepted value. Using the calculator at http://www.freecalc.com/fricfram.htm came up with these numbers for the dynamic head for the plumbing at various flows. All pipe is 2" except the bog is 1 1/2":
I am assuming I can split up the flow as I did with the highlighted cells. By adding them all together, I get 7.6 feet of dynamic head. Does this look right?
For static head, the main output is a drilled boulder 3 1/2 feet above the top of the pond. We want the majority of the flow here. There is also a bog that it output about 1 foot above the pond water level. We only want about ~800 GPH there, judging by our current pump. The equipment is in a shed about 6" above pond water level.
Using the values from the spreadsheet, at 4000 GPH I have about 7.6 feet of head. Zak says the sieve at that height adds about 3 feet of static head. The boulder adds another 3 1/2 feet of head. Or does it? Should that be calculated from the pond water level or the sieve water level? That would reduce it to about 2 1/2 feet.
Then there is the Ultima II 4000 filter. Man, the numbers for this thing are all over the place. Aqua Utraviolet says:
"The filter flow loss ranges from 3-8ft of head, depending on how dirty the filter is"
and also says:
"*For example: If you have a 2,000 gallon pond and are using an Ultima ll 4,000 Filter the pump you
choose must be rated at 4,000 gallons per hour at 10 feet of head pressure."
Well this makes no sense. Between my static head and the dynamic head in the rest of the plumbing I have about 14 feet of total head before even adding the filter. If I get a pump that produces 4000 GPH at 10ft of head, I won't get anywhere near 4000 GPH through the filter.
Looking around here and other places on the interwebs, there seems to be a rule of thumb to add 10 feet of head for a bead pressure filter. Adding that to the other 14 feet I have calculated, that pushed me beyond the 1/2 HP Artesian 2 pump. In fact, it pushes me into some wierd nether world where no pumps exist. The low head pumps stop at about 24 feet of head. Then the high head/high pressure pumps kick in at much higher flows for 24 feet of head.
This is driving me NUTS! OK. I can be a bit obsessive (ask my wife), but I just don't want to buy the wrong pump and regret it months from now. My gut says the 1/3 HP Artesian 2 will do what we need. But it's driving be crazy that I can't get solid numbers to back that up. Any help would be MUCH appreciated.