PVC Elbow effect

FastFish720 · 08-14-2003, 09:40 AM

How much effect does an elbow (2) have on the return on water. Here is my situation. I mis-measured by a 1/4 on my acrylic. Grr so it doesn't fit in my stand. So I think now it's going in back of the stand. Here is the plan: The water will drop through a standpipe and elbow 90 degrees then elbow down into my sump. From there it will be returned up to and elbow then horizontal then elbow up again. Will this have a major effect on my water flow on the return part.

Graham · 08-14-2003, 09:46 AM

It depends on 1.) how much water the pump can move at the given head and less so on 2.) the pipe's diameter.

Likely, there will not be significant reduction unless you have a weak pump that doesn't perform well under head pressure.

Crevalle · 08-14-2003, 09:49 AM

I would be more concerned about your overflow, as it can potentially limit your pump if water isn't getting to the sump fast enough. If your overflow has a 90-degree elbow on its way down to the sump, it's going to decrease your flow to the sump by a noticeable amount (gph). Keep in mind the gravity is the only thing you have going for you on your overflow--this is why most go straight down to the sump. Perhaps I didn't understand your question, as I've never heard of a 90-degree elbow installed into overflow tubing.

The 90-degree elbows on your return will decrease flow somewhat, but shouldn not be amount to anything absurd. I have four 90-degree elbows (including a "T" at the top) on my return (powered with a mag9.5), and I still don't have my pump going full throttle because the lifereef can't keep up.

clyde · 08-14-2003, 10:06 AM

if you cant go straight, use a 45 degree then you will have less head

OR use flex PVC/Tubbing, and glide it down to sump instead ?

Crevalle · 08-14-2003, 10:08 AM

I agree with Clyde--flex tubing is generally the way to go with overflows. Mathematically speaking, I'm not sure whether or not two 45-degree angles would be better than one 90-degree angle, with respect to gph. Anyone?

FastFish720 · 08-14-2003, 10:44 AM

Does anyone know where I can get flex tubing for 1.25"

FastFish720 · 08-14-2003, 10:45 AM

BTW will this stuff stay in a ball valve cause I don't want to glue it or have it falling down.

Crevalle · 08-14-2003, 10:57 AM

You'll have to get an adapter if you want to hook up flex tubing to a ball valve. The tubing (and adapter) can be found at HD and Beisswinger's. I can personally say that the HD on Stinson Blvd has everything you need. I can't speak for their other locations, as they all seem to have different policies (some cut glass, while some don't carry it, etc.)

Graham · 08-14-2003, 11:04 AM

I called that HD and asked for flexible PVC tubing and they didn't have a clue.

I ordered mine from Aquatic Ecosystems for about 1/2 the price of what Menard's is selling it for. They recommend that you use a special type of PVC cement. Whether or not this is fact, I don't know, but I figured $4 isn't too much to play it safe.

Also, you don't need an adapter to connect flex to a ball valve. It goes right in. See this:

The intake on my closed loop is a 1-1/2" ball valve connected directly to flex PVC. No problem at all.

FastFish720 · 08-14-2003, 11:17 AM

Thanks guys

Crevalle · 08-14-2003, 11:18 AM

FastFish--the flex tubing (a truckload of it) is on the other side of the PVC fittings isle. You absolutely cannot miss it.

Graham--I see you fitted your flex-tubing into the ball valve. Generally speaking, you don't want flex-tubing on the inside of PVC--it goes on the outside, and you then use hose clamps for added security. Your method may work for you, but it isn't the most orthodox way to accomplish what Fastfish has set out to do. It is by no means common practice.

Perhaps large diameter tubing is different?

Graham · 08-14-2003, 11:53 AM

Quote:

Originally posted by Crevalle
Graham--I see you fitted your flex-tubing into the ball valve. Generally speaking, you don't want flex-tubing on the inside of PVC--it goes on the outside, and you then use hose clamps for added security. Your method may work for you, but it isn't the most orthodox way to accomplish what Fastfish has set out to do. It is by no means common practice.

I ordered the 1-1/2" flex PVC. It fits inside a 1-1/2" female PVC end. Why would they size them this way if they weren't intended to be used on the inside? Also, the instructions on the "PVC cement for use with flexible PVC tubing" list instructions only for use as I have done above. The ID of the tubing does not fit any conventional size of PVC. Plus, the cement is permanent. It's not goig anywhere - the bond is just like normal PVC.

I'm not saying you can't do it like you suggest, but they are sized by OD, not ID.

Crevalle · 08-14-2003, 12:17 PM

Graham--I realize what you're saying. The point I wanted to make to FastFish is that the most common method of attaching flex-tubing to PVC is by using hose clamps (w/ flex fitting over the PVC). You could make any number of methods work.

I'm going to shut up now because I don't want this to turn into an argument. Different strokes for different folks.

Graham · 08-14-2003, 12:34 PM

NO problem.
Definitely no argument here...

Twins Guy · 08-14-2003, 12:42 PM

i think its important to clarify that true flex PVC is different than flex clear vinyl or many of the other flex tubings available (and don't yell back that pvc is PolyVinyl Chloride-we know). graham-i think alot of us are unfamiliar with the true flex PVC you're using. how rigid is that stuff? and flexible (do you need heat or...)? does it come on a roll (or in lengths like regular PVC)-that might be the most simple question?
tg