diy counter currnet PS

poo-tang · #1 03/16/2007, 05:54 PM

yeah i wanna build a counter current PS. it will be external. do i pump water into it or pull water through it. i would like to feed it first from my overflow and pull the water through it too the sump? sorry just confused as to how the water flows.
the way i described it won't work will it...cuz i still have to pump the water back to the display?

Keelay · #2 03/17/2007, 12:30 AM

You can pump or let gravity pull water through it.

The overflow feed will work, but you will want a way to regulate the water flow so that it doesn't fluctuate with the return pump's flow rate, because it will vary over time. Especially if you have a prefilter on it.

That means you would want two overflow drains one to send to the skimmer, the other directly to the sump.

You could pump as well, but that will cost money for the pump and the e-bill every month to run it.

No matter what you will need to have a pump in the sump to return water back to the display. This pump doesn't have anything to do with the operation of the protein skimmer.

poo-tang · #3 03/17/2007, 05:26 PM

perfect answer, thanks. now to determine my sump pump size and i will be ready.

Keelay · #4 03/18/2007, 01:28 AM

Good question. Some people make the mistake (IMO) of trying to use the return pump to accomplish the tank flow requirements. Just get a big enough one to accomplish your sump/skimmer filtration goals.

1) It's more efficient(and therefore cheaper) to generate flow using a closed loop or stream pump in the display tank.
2) If your whole system relies on one pump then you have a single point of failure with potentially disastrous results. The corals depend on flow. Even if you have another ready to swap out, it may be 8 hours later when you get home from work that you discover it.
3) depending on how you set up your refugium (if you do that), then having too much flow through the sump can hamper the success of the refugium.

The skimmer usually is targeted to 2-3x turnover of the total system volume per hour. Example: 100 gallon tank + 30 gallon sump = 130 gallons total. 2x = 260GPH - 3x = 390GPH. If your overflow drain is plumbed to the skimmer and lets say 70% of the overflow goes to the skimmer, then you'll want about 4x the total volume of the system as your return pump flow. Example 4x = 520GPH.

Use the RC head loss calculator on the RC main page to determine what different pumps will push accounting for the head loss due to height and plumbing fittings.

poo-tang · #5 03/18/2007, 07:37 PM

i read...from snailman's diy cc skimmer...from Escobal's book...that you want to turnover about 2x per day...but that there is a formula for figuring this out...because it actually isn't as simple as doubling your total volume, or 4x if you go 50/50 , PS/Sump...which i think i will do. Is this method still used or am has it been x-ed out?.anyways my total vulome is looking to end up in the 160 gallon range minus water displacement from rock, is this accounted for or deemed negligible?
so your equation says i should get a pump between 640-960gph 160X2-3 and doubled as it will recieve half of the flow.whereas snailman's says, i looked the chart up, basically multiply by .75 = 126gph. this is quite a difference.

lakee911 · #6 03/18/2007, 08:52 PM

What's PS?

poo-tang · #7 03/18/2007, 09:51 PM

protein skimmer

SeaView · #8 03/18/2007, 10:07 PM

Why a counter current skimmer? Will probably cost just as much to build as a needle wheel/venturi type skimmer mod. But the needle wheel kick major butt over the CC skimmer.

Keelay · #9 03/18/2007, 11:40 PM

I agree with SeaView, there is certainly a consensus that Counter Current skimmers are not as efficient as needle wheel or some of the other types of skimmers. I haven't tried a counter current so can't speak for myself, but I would go with consensus. I don't like the idea of having to change air stones every so often.

I personally built my own beckett skimmer and have not been disappointed. I am curious about a needle wheel. The concept makes sense to me.

poo-tang · #10 03/19/2007, 06:04 PM

yeah i agree...i've been researching and found that cc was the most efficient. that was one noght of reading...last last f3-4 nights i have been reading needlewheel sounds like what everyone is using...i hope not just here though. i am on one other site and they have similar opinions. i think i will just build a needle wheel.
what about the flow through the skimmer ie my earlier post. i think i might size my pump out in the 1200gph range and send half of that through my skimmer.
does the " the taller the better theory hold true for needlewheel skimmers"? i was thinkinking of making it at least 4 ft tall and with six inch pvc. i may even let the height of my tank dictate the height of the skimmer inlet if taller means more efficient.

SeaView · #11 03/19/2007, 06:30 PM

I think a needle wheel skimmer will be more effective without the body needing to be that tall. Take a look at some of the designs on the Octopus skimmers to get some ideas. However, you may need a tall neck. Those needles produce tons of foamy bubbles.

Keelay · #12 03/20/2007, 02:51 AM

Quote:

Originally posted by poo-tang
yeah i agree...i've been researching and found that cc was the most efficient. that was one noght of reading...last last f3-4 nights i have been reading needlewheel sounds like what everyone is using...i hope not just here though. i am on one other site and they have similar opinions. i think i will just build a needle wheel.
what about the flow through the skimmer ie my earlier post. i think i might size my pump out in the 1200gph range and send half of that through my skimmer.
does the " the taller the better theory hold true for needlewheel skimmers"? i was thinkinking of making it at least 4 ft tall and with six inch pvc. i may even let the height of my tank dictate the height of the skimmer inlet if taller means more efficient.

I'm not an expert at needle wheel designs. I did however build and then rebuild, and then tweak, and then mod, my Beckett skimmer. Anytime you start on a project like this with this many variables, your bound to learn a few things along the way. That's part of the fun. But it is a lot of work.

That being said I would recommend starting with a known design and go from there. You've brought up three issues that need to be addressed.

1) I'm not sure what you meant by splitting up the 1200GPH. You have to have a dedicated pump for you skimmer if you build a needle wheel. The bubbles are sucked into the pump via a venturi and the pump impeller makes mince of the bubbles generating a nice foamy output. So you can't split the output.

2) Even 600GPH is way to much flow through a skimmer, unless you have an enormous skimmer and a massive tank. (300 Gallon+)

3) A 4' tall skimmer will generate a lot of back pressure on your pump. This I understand will limit air induction. I'm not an expert (others chime in here), but the height of the water column plays a balancing role in making an effective skimmer. True a taller column is typically better in theory, but if it negatively effects the bubble generation then it might be for naught. If you're going for ceratin volume, go with less height more width.

I hope I'm not too off to say you seem very eager to start on this. I don't want to discourage you from doing this, but I would either recommend waiting and learning more first and weigh your options. You will benefit by having a better skimmer and save yourself a lot of rework.

Otherwise if your ready to go or really need something now and aren't willing to wait on this, take a stock design and just implement it. These have been tried out and most of the bugs and balancing / tradeoffs made to get a reasonable design.

Randy has a simple, easy to build needle wheel design that a few have built here in RC with success.

http://www.randystacye.com/diy_needle_wheel_skimmer.htm
or
http://www.randystacye.com/diy_needl...l_skimmer4.htm

There may be other designs as well. Anyone else have suggestions here?