Flat strainers w/ bulkheads on CL's and overflows

[MrSpiffy]

I FINALLY found some strainers WITH bulkheads available online that aren't the pointy or cone-shaped strainers that you can find one most aquarium plumbing sites!!! I found some flat strainers, similar to one that I saw posted a month or two ago by someone. It's technically made for a spa, but it's flat and it comes with a matching bulkhead! You can get them in 2.5" or larger, and I think these would be awesome for closed-loop systems! Here's where I found them:

http://www.spacare.com/index.asp?PageAction=Custom&ID=56

An entire assembly for a 2.5" one is $19, or a little extra if you want black (or other colors) instead of white. Do note that it appears that the included screws are metal. So you'll probably want to find plastic replacements for them, or see if you can find a way to attach it without screws so you can clean it easier.

If you search for spa suction assemblies, you'll probably be able to find these all over.

I'm excited!!! Anyone else excited?!?! I think these will look much better than the current threaded strainers, and give us more room in our tanks!

 

[MCary]

The problem is, a flat screen can have suction problems. With the cone shaped screens, any critter coming in contact with the cone should be able to easily break free. But anything up against that screen can get stuck.

That's why the cones were designed the way they are. Not because no one ever thought of the other way before.

Mike

 

[MrSpiffy]

I guess I'm not really seeing how it'd be any different, simply because the holes are in a flat pattern instead of a cone-shaped pattern. Maybe because it's a larger flat surface area, insead of one that's wrapped around in a cone shape? It still has the same amount of suction, assuming equal area in openings. And if it's something like an anemone stuck to it, it's going to need to be removed by us anyhow. And if you have so much suction in your C/L that you need to be worried about critters getting sucked on, perhaps two inlets for your C/L are necessary. Personally, I think the smaller holes in the flat screen would be less damaging to anything getting stuck on it than larger holes, as it wouldn't pull as much of the animal through the strainer (such as tentacles/polyps/legs/fins, etc.).

Now, of course, these are all opinions, and I could be entirely wrong on all of them. If I'm wrong, it'd be nice to find out now instead of later. I just see these as more pleasing to the eye than the cone-shaped strainers.

On a side note... it would be nice to have some sort of auto shut-off in case something DOES get sucked onto the screen. Anyone heard of this? I would assume it would be as simple as monitoring RPM's in the pump, and when there's a jump up in RPM's it would shut off. I realize that most pumps probably don't have wiring to monitor RPM's, but this would be nice to have.

 

[MrSpiffy]

Anyone have any other thoughts on these?

*bump!*

 

[mr pink floyd]

what hes saying is becasue its flat, theres less area for water to be pulled in, so the suction will be stronger in that small area

if it was a cone shaped one, there woudl be lots of area, making the suction less in spots, so things can pull away

 

[seanb]

I bought 1.5" spa screens from here:
http://discountspaparts.com/asccustompages/products.asp?cartID=&affID=&categoryid=291&navParent=0
My tank has been up and running for a month and the spa screens have been great. They have openings on the side edge as well as the face and so far I have had no problems with the suction. There are 2 1.5" intakes supplying my sequence dart.
When I put in a tuxedo urchin this week he loves to hang out by the intakes. I first I was concerned he was stuck, but he travels around the tank and then parks by the intake and seems fine. They work great and I don't have conical strainers sticking out into the tank.
I bought just the covers and there were no metal parts.

 

[namdrib2]

MrSpiffy you are correct in that it has to do with surface area not shape. But it is not the entire surface area but what is called the free area (the sum of the square area of the holes/slots). Typically, cones have more free area that the flat strainer, which is where MCary and mr pink floyd are correct, but not in all cases. Because of this lower free area the velocity through the flat strainer tends to be higher. Based on the picture from the web site that you linked it does appear that this strainer has sufficient holes in it to keep the velocity down. The strainer you linked is good for 96 GPM/5760 GPH which is well above the capabilities of the pump you intend to use I'm sure. The suction velocity will be determined by the head loss on the pump and the pumps rated output. I assume that you will be in the maximum range of 25 GPM/1500 GPM which is a velocity of 3 feet per second through the strainer. Most fish and inverts should be able to get themselves un-stuck from the strainer should they in a remote possibility get stuck.

BTW they link you posted has the smallest one at a 1.5" which may be better suited for 20 gallon tank, if that what it's for.

My two cents.

 

[MrSpiffy]

Thanks for the replies! I appreciate all the input. namdrib2, you are correct in that the pump I intend to use will be significantly smaller than the rated flow for that screen. I also intend to use one on a 40G Breeder tank I'm planning out. My 20G is already set up, and I have no intention of breaking it down so I can drill it.

Also, the fluid flow mechanics are definitely something I'm familiar with, being a mechanical engineer. So I understand that smaller holes = higher velocity through the holes. But, I figured I'd use one larger screen/bulkhead or two smaller ones to compensate for the higher flow rate. My pump for a closed-loop system would likely be in the 400-500GPH range, which, ends up being about 8GPM. According to your calculations, this would put it in the 1 ft/s range. (More than sufficient flow, and significantly lower invert-sucking-onto-it badness.)

In case you're wondering on why the lower flow rate, it's because I intend on keeping softies and LPS. There's no SPS in my future as of right now. I'm sure 20x turnover (including return pump, which is roughly 250GPH after head loss) is plenty for what I intend on keeping.

Also, it appears that the strainers actually twist-lock onto the bulkheads they come with. So, unless it's a model that has more than one screw, it's not necessary to worry about screws. I'm sure they'll hold in place by themselves. If not, I'll make them stay! :lol:

 

[sabodish]

do they have them in 2"??

 

[Slickdonkey]

If you're handy, build a strainer out of acrylic. Check out the pictures I posted in this thread:

http://www.reefcentral.com/forums/showthread.php?s=&threadid=924779

 

[MrSpiffy]

Thanks for the idea and pics Slickdonkey. That's definitely an interesting twist on intake strainers. I'm not sure if I'll use it, though, as I think the spa strainer will take up less room in the tank. It's only a 40G Breeder tank, so it's not that big to begin with, and I want to conserve as much room for fishies and other livestock as possible. It's definitely a good idea for larger tanks, though!

sabodish, I did provide the link. But I visited hydroairusa.com to verify their specs, and it looks like the 4" and 5" strainers have 2" I.D. bulkheads, or fittings designed for use with 2" PVC pipes, rather. The slim and high-volume strainers have 1.5" slip fit fittings.