Comments: I bought this thinking it would work better than the hole in th return line trick to stop siphon, but after all three were in for a day they won't completely close. It is just shuttering open closed really fast. Realy loud and annoying not to mention it doesn't completely close all the way. I am going back to the old hole drilling.

Comments: Not sure what else to say. It's expensive for what it is but it works great.

Comments: We have used several different check valves and this is the first valve that has not made the hammering noise when the pump is turned off. I am ordering a 3/4 inch slip to replace another check valve we have that just hammers away once the pump is turned off and does not stop the backflow of water into our sump.

Comments: It just stop the water level in the right way.

Comments: This bad boy solved my problem. When I would shut my refugium pump down, water would flow from the main tank back into the refugium and flood! I installed the True Union Swing Check Valve and tested it.... guess what? NO FLOODING!!!!!! A+ product!!!

Comments: With all the thunder storms and following power outages this summer...I have peace of mind , now that I have the check valve in place . Anti-siphoning stops are not to be trusted in a marine tank .

Comments: It's always nice to have a true union valve in your plumbing to help with disassembling and cleaning pipes, but the check valve itself doesn't always close fully when the power goes out. Try installing in a vertical position to help solve this. If your sump can't handle the back flow, this is an good fix.

Comments: Excellent product no glue no tape nothing needed works great so far

Comments: I like the fact that it is transparent, so you can verify that it is properly functioning.

Comments: This replaces a spring type valve that I paid dearly for at a pond store. The spring valve clogged with pond particles/algae and never worked well. I was fearful of a power outage in my absence. Replumbing this spring led me to look around for an alternative and I found this site and the discovery of this clear valve. Its true that it works vertically or horizontally. Its great to be able to see through the valve to check the function. I tested for backflow from the two split lines from the upper pond and the filter system. It works great! For ponders, I recommend this valve highly.

Comments: The True Union is solidly made of quality materials.
<br />Installation with regular PVC is easy and effective.
<br />The unit consistently prevents backflow. It seals so well I have to loosen the union flanges to get anything to drain

Comments: Having installed some of these check values in a new and large system (800 gallons), I was dismayed to discover that there is a "hammering" effect when the pump stops pumping. Water trying to return through the check valves causes the valves to open and close with loud thumps for a good 4 minutes before the water finally stops backfeeding. I was upset to motice that this "hammering" caused enough revirbiration through the plumbing that it actually caused some live rock in one of the tanks to shake free of their "shelves" (custom made to allow viewing of all live rock) and toplle to the bottom of the tnak. I am wondering if they can be redesigned with some sort of spring mechanism that helps to apply a small amount of pressure to the flap once wtare flow ceases, so that when the flap closes, it stays closed and there is no "hammering" effect. I love the unions on the check valve. I just am worried that if the "hammering effect isn't corrected, I could have a small problme on my hands if I experience a power outage. The check valuse are not suppose to "hammer" once the flow from the pump stops.

Comments: Good product, does what it is supposed to do. Only problem is that the o-ring seal on the true union is on the opposite end of the true unions you can at the hardware store. Thus if you want to move this valve to another location you would have to get the true unions from the manufacture, SPEARS I think in this case, instead of your local hardware store.

Comments: I've used this product before on the siphon line below my 54 gallon tank. It has always performed as expected. We are sometime subject to power failures at my office where the tank is located and I rest easy knowing that I won't come to work and find a flooded floor dried out fish.

Comments: I purchased 3/4" slip check valve to prevent back flow back into my sump. There appears to be minimal pressure loss and it's see through so the water flow and flapper are visible. No leaks through the threaded union either. Though it's a little pricy (3x-4x vs. HomeDepot)I would highly recommend the valve

Comments: Nice valve. The flapper seats securely with no head and requires very little pressure to open. As the flapper moves out of the flow path there is very little resistance unlike with most spring loaded valves. As it is clear, it is very easy to see any obstructions (snails, macroalgae). My only concern is how long the rubber flapper will last in saltwater.
<br />I can't find any information on if replacements flappers are available.
<br />

Comments: The one inch is very BIG but, plums in with no problems. Great way to stop back flow into your sump. NOTE: If your pushing alot of water into the overflow box and you have the ash tray effect"UUUUUUUU" at the top of the over flow box. You will still get some back flow to the sump from the over flow untill it levels out below the U on your over flow box.....

Comments: well made & worth the price..

Comments: If you need a check valve, then this is the one for you. Very little restriction, and easy to clean if need be! Great product

Comments: Man this check valve is great! It does what it's suppose to do babygirl! I Love it!! No water leak's or nothing uhh!

Comments: This thing is awesome. Well worth the $20 for the safety it makes. Best built check valve I have ever held.

Comments: Good price, closes great even under very low flow....

Comments: Very happy with True union swing check valve.Very little if any restriction on return pump and no syphon effect filling sump when power is off for maintenance.

Comments: Best parts -
<br />The body can be replaced easily and it can be mounted vertically and horizontally!

Comments: Third one of these I've bought and they all work great. The see through plastic lets you know when it may need cleaning and its very easy to take apart.

Comments: Nice to be able to clean and see if there is anything in the check valve. With it being a union it is easy to clean.

Comments: I use this check valve to prevent back flow from my protein skimmer into the sump during a power outage. I have yet to find one of these that still functions after 12 months. The salt water must deteriorate the rubber to the extent that it becomes hard. The "flapper" then does not return to the closed position and allows backflow. This is a completely sealed unit, there is no maintenance or replaceable parts.The good thing is that with this type it is easy to replace because of the union connections.

Comments: The check valve worked as advertised. Easy to plumb and incorporate into your setup. A little bigger than I thought, but it works fine. Stopped the siphoning and back flow once the pump was turned off. Definitely suggest this for every reef/FOWLR tank setup.

Comments: Functions very well, not a good candidate for applications where you have limited space. This thing is BIG!!!!!

Comments: I replaced a manual ball valve with this check valve, which I'm using to prevent siphoning back down into the sump. The valve installed very easily, the clear PVC provides a nice view of water flow, and the union allows easy removal of the pump (and of course the valve). The valve is made very well, and looks like it will last a long time.

Comments: Great Product!!! I own 2 of these now. Wouldn't go any other way for a large capacity check valve. Very sound construction and easy to maintain. Check valve completly seperates from system for maintenance cleaning.

Comments: The union check valve is great. It allowed me to get my tank up and running with no worries about water draining out of my pump, so when start-up after a power outage I don't worry about a dry pump. The only thing that I dislike about the check valve is that it is very big and bulky. Other than that it is a great idea