where to buy pvc

[alan j t]

Just did the order and i hope I bought everything i need. 50 bucks just for all the fittings. I some pvc pipe at lowes already.

 

[alan j t]

I fotgot to mention they had a clear check valve union ,like 12 bucks. I had to get it. Will post pics of my new stuff ....I guess i should start a build thread too huh???

 

[CuzzA]

No need for a check valve in a properly setup system. It will fail anyway so do not rely on it.

 

[Bent]

No need for a check valve in a properly setup system. It will fail anyway so do not rely on it.

I like using them just for ease of restarting the system without air burping all over the place.

Just don't rely on them, as you said, as your primary safety measure.

 

[alan j t]

Sounds like wise words. I will make sure both are properly setup.

 

[CuzzA]

They will significantly reduce the efficency of a return pump because they require pressure to open the valve, which reduces pressure that would normally free flow to the tank. Furthermore, they create a substantial amount of friction which results in even less flow. IMO they do more harm than good.

 

[alan j t]

Really!!?!!??

 

[balz3352]

I'm planning my setup right now. I also found the unions to be lacking at the big box. But this is what I'm doing. Actual piping lowes. Unions and gate valves brs

 

[CuzzA]

Really!!?!!??

Yes.

Friction loss defined. https://en.m.wikipedia.org/wiki/Friction_loss

Here are some friction loss tables. https://www.plumbingsupply.com/ed-frictionlosses.html

So let's use for example 3/4" pipe which is probably the most common size for a return and see how certain fitting effect the flow. This table illustrates the equivalent length of pipe that a fitting has on the water.

• A swing check valve is equivalent to adding 6.86 feet of pipe to the run.
• A 90 degree elbow is equivalent to adding 2.06 feet of pipe to the run.
• A 45 degree elbow is equivalent to adding 1.10 feet of pipe to the run.
• A tee where water is coming in from the branch side is equivalent to 4.12 feet of pipe to the run.

Now couple this with the fact that organics and inorganics will build up in your plumbing and with the fact that everyday past the last time you cleaned your return pump efficency is reduced and depending on the head height of the run, you could have substantially less flow than you think you have.

Is it going to crash your system? No. But if I want to put x amount of flow between my display and sump, all of this needs to be taken into consideration.

Finally, due to the enviornment of a marine aquarium the check valve will need to be cleaned often as organic and inorganics will build up and prevent the valve from shutting. If your sump cannot handle the volume of water that will siphon back from the display you're going to end up with a flood. It is much better and is common practice to drill a siphon break in your return at the water level in the display and to make sure your sump can handle the volume of water that will come back to the sump from within your overflow and plumbing.

The bottom line is fittings reduce flow. We want as few as possible. And as illustrated a check valve reduces flow substantially more than any other common fitting we typically use.