SCWD opinions please. Pros, cons and the pumps you used them on

OK, I want to follow this thread but first I gotta ask what the heck an SCWD is. :)

http://thumbs.ebaystatic.com/pict/2003203241286464.jpg (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200320324128)
http://www.melevsreef.com/video/scwd.wmv

Hmmm.... I've heard about those (not by the acronym, though) but never seen how they work. Intriguing.

Do they typically just manipulate your return? Or are they independent of all the other plumbing, running like a closed-loop?

You need at least 2 returns. It can be a simple form of a wave maker and seems to last awhile if not pushed at it's full potential for a long while. Which is why I am looking towards the 1" and under powering it by about half.
Will maybe be running this from my fuge on my 180 and then the seperate closed loop off of a reeflo barracuda

Just did a little reading at melevsreef. He used it closed-loop, but I've got the wheels turning here wondering if there would be a way use this and split my single return into two. I really like the idea of that over paying big $$$ for a wave controller and controllable PH's.

We have one on a 29g, 30g and a 75g. The best info is on Melevsreef.com. They come in two sizes. It gives wave action to the tank. Hope this helps!

Yes, you can do that. I was planning that when I was still planning to keep my 75 non RR. I was going to run one of these over the top of the tank at each corner pointed to the middle. I still might as my Mag 9.5 might be too much to come out of those 2 locline returns in the overflow in the 90.

http://a1272.g.akamai.net/7/1272/1121/20060410162845/www.drsfostersmith.com/images/Categoryimages/normal/p_25768_FS34720PZ.jpg

We have split ours so you have two returns and two fan off of each return.

Nice!
Would love some pics and/or opinions

Yes, you can do that. I was planning that when I was still planning to keep my 75 non RR. I was going to run one of these over the top of the tank at each corner pointed to the middle. I still might as my Mag 9.5 might be too much to come out of those 2 locline returns in the overflow in the 90.

FWIW, I found that a 9.5 was too much on my 90, despite people saying "there's no such thing as too much flow". I swapped it for a Mag 5 and the flow in the DT is better (in the sense that things aren't getting blown too hard) and the skimmer in the sump pulls more due, I guess, to more contact time. Heat is less of a problem now, too, with the smaller pump.

My back glass is painted on my tanks so i can't get a picture for you. Picture the SCWD in the middle of the back of the tank but a little lower, come off the sides with pvc pipe to the edge of the tank, come up the sides and over with pvc, then attach the black lock line conector, line and fan. At the bottom of the SCWD we connected a flexable tubing to the pump, set how many seconds for the flow to go back and forth between sides. After about two months we decided we wanted more flow and went with a bigger pump. Hope this will give you a mental picture of what it looks like.

Well it's on my 75 now, lol. Now that I think about it, my skimmer has been pulling less gunk since I put the 9.5 on instead of the QuietOne 2200 I had. Maybe I'll see if someone wants to trade for a 7. The tank will have about a 6' head as I'm planning to make the top rim of the tank about eye level for me so I don't have to bend down to see stuff on the sand bed.

Sweet! What SCWD (3/4 or 1") and what pumps?

I have a 3/4" SCWD running on a mag18 return on my 185G. I love, love, love it. No leaks, no noise, no power requirements, and it gives decent random flow in the tank via the 2 return lines.
I didn't just read Melev's article, but have in the past. I believe he mentions something about the time period between "switches". The more water you push, the quicker the switching occurs. Mine changes about every 5 seconds on the mag 18.
No hesitation whatsoever to recommend this product.

I have never ran one but I worked on a tank that runs the 1" on a 1740 coralife pressure pump and it was awsome wave action in the tank. i am not sure of the switching intervels but it was perfect for the 210 it was running in. I'm sure they create some head pressure loss but not sure how much?

I run a 3/4 on my 180 using a mag 9.5.

These things get a bad rap by people as being troublesome but I have nothing but positive things to say about mine.

I bought mine used for 20 bucks and it has been in service for a while now on two different tanks.

I have only had to clean it when I changed it from the 125 to the 180 but I would recommend cleaning it quarterly or every six months.

Why spend hundreds on expensive gear to alternate current? I use mine connected to two returns which are used to only keep the surface moving.

Alright, I guess I'm sold and need to order one. Now a question about what would be the best way to install it. I have 2 loc line tube returns coming out of the overflow. If I did this, I would add the piece that goes over the tank like pictured above in each corner. Should I tee off before the SCWD giving a constant return out of the overflow pipes and only alternate the corners, or should I put the overflow pipes on one side of the SCWD and the corner pipes on the other side?

I have a 3/4" tube going to a tee which feeds both returns.

Alright, I guess I'm sold and need to order one. Now a question about what would be the best way to install it. I have 2 loc line tube returns coming out of the overflow. If I did this, I would add the piece that goes over the tank like pictured above in each corner. Should I tee off before the SCWD giving a constant return out of the overflow pipes and only alternate the corners, or should I put the overflow pipes on one side of the SCWD and the corner pipes on the other side?

Mine is currently set up so that the SCWD alternates flow between the two 3/4" return pipes in the overflow, similar to your existing setup. Each of them is pointed in opposite directions, so I get about 3 seconds of flow to the left, 2 seconds of combination flow as the SCWD changes direction, and then 3 seconds of flow to the right (repeat). Your time periods may vary, depending on the pump you ultimately use.
I'm even thinking of adding 2 more SCWD's (1" version) to my CL, using the 2 SCWD's to alternate flow between the 4 CL outlets. Each of these 4 outlets has a loc-line Y, for a total of 8 nozzles.

I use a 3/4" SCWD on my 20" cube. It's hooked up to a Little Giant 3 (I think 700 gph?).

I think there are a couple of key things to keep in mind when you install it. First, make sure the intake to the SCWD is in a place where it will not suck in sand and other goodies. I drilled a PVC pipe as the intake and keep it behind the rock.

Second, realize that at some point it will need to be cleaned so install it like you are going to take it out. That means make sure you have valves on both the output and input off the SCWD.

3rd, when you initially set it up, you will here it switching. After a day or two, it will quiet down. I can't hear mine now over the slight hum of the pumps.

I didn't know you could put that much water volume through the SCWD. I might need to upgrade my pump.

I believe the website says they can run anywhere from 50-1400 GPH, but the more flow, the faster the switch. I believe with a little head pressure, mine runs about 1600 GPH on the Mag18 with no issues.

Loren, you say the "intake" of the SCWD? I thought these things ran in-line. I planned on putting a 3/4" in my return line and have it tee off to the left and right return bulkheads.

I thought these things ran in-line. I planned on putting a 3/4" in my return line and have it tee off to the left and right return bulkheads.

Correct. You should have no issues.

Wow guys thanks for all the responses and info.
Looks like I'll be going with the 1"

I was thinking in a closed loop scenario. I suppose you don't have to use it in a closed loop although I don't know why you would want to restrict your returns.

What I mean by intake is the intake for the pump that feeds the SCWD. Sand and other goodies might make it through the pump just fine, but it will mess up the internals of the SCWD and cause it to fail.

Loren, you say the "intake" of the SCWD? I thought these things ran in-line. I planned on putting a 3/4" in my return line and have it tee off to the left and right return bulkheads.

Wow guys thanks for all the responses and info.
Looks like I'll be going with the 1"

I think the 1" can be opened for cleaning. That might have been in an earlier post.

Don't know.
It will be on the return pump from the sump while the closed loop will be on it's own for constant turbulance