plumbing help needed !

rickster

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In a bottom drilled tank , with 2 returns that are T'd together do I need 2 separate check valves or one would be ok?
and Should I put ball valves on in/out of UV so I can service it, or just service it from the 2 unions it has ?
Thanks,
Rick
 

Red_Beard

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Depends on where you put it, the check valves will have to be placed so that every path lower has one. If 2 lines are teed together you could put one after they are joined, or o e on each leg of the tee after they separate.
I think valves befor the uv would be nice, then you can isolate it if/when needed.
 
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rickster

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Depends on where you put it, the check valves will have to be placed so that every path lower has one. If 2 lines are teed together you could put one after they are joined, or o e on each leg of the tee after they separate.
I think valves befor the uv would be nice, then you can isolate it if/when needed.
Thanks, I was thinking of putting it at the bottom by the pump, that's the only space I have so I can service it, does that make any sense? I have a very tight space under the tank in the cabinet.
 

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It also depends on which type of check valves you plan to use.

Many "hobby grade" check valves use a "swing check" design which typically don't seal very well unless they have a large amount of back pressure on them (i.e. vertical rise between the check valve and the surface level of the tank).

However, if you are prepared to spend a few extra bucks, opt for the "piston-check" design ... they will be far more reliable over the long run, and will still work with relatively little amount of back pressure. They are also sometimes called a "Wye Check Valve" based on the shape of the body construction.

Here's an example:

 

redfishbluefish

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When you say bottom drilled, are this just sitting out in the bottom of the tank with nothing around, or are they behind an overflow wall typically in the corners of the tank? If they are in an overflow, you should include a stand pipe which would minimize back-flow to the sump.

If you have two holes in the bottom that simple sit there on their own, I'd have the plumbing come off these bulkheads, loop above the water level of the tank before going back to the sump, and include a reverse check valve at the top of the loop. This check valve will break the siphon, saving your sump from overflowing. I do not like backflow check valves used in conventional way. It's not a question that it will fail, it's simply a matter of when they will fail. Here's an example of a reverse check valve use by Melev's reef.

 
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rickster

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It also depends on which type of check valves you plan to use.

Many "hobby grade" check valves use a "swing check" design which typically don't seal very well unless they have a large amount of back pressure on them (i.e. vertical rise between the check valve and the surface level of the tank).

However, if you are prepared to spend a few extra bucks, opt for the "piston-check" design ... they will be far more reliable over the long run, and will still work with relatively little amount of back pressure. They are also sometimes called a "Wye Check Valve" based on the shape of the body construction.

Here's an example:

yes , thats the one I bought, do I need 2?
 

TexanCanuck

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You need to put one check valve on each line that has a direct path from the display tank to the return pump discharge.

So ... if I understood your original posting correctly, it sounds like there is a single line coming from your return pump that connects to the inlet of your UV, and then the outlet of your UV connects to a "T" fitting, from where your return splits into two separate return nozzles inside your display tank. If I got this right, I would simply place ONE check valve between the discharge of your UV and the "T" fitting.

You can of course put one check valve on each return nozzle (i.e. between the T fitting and the nozzle itself), but this is just adding work in my view.

If I didn't understand your plumbing arrangement correctly, please clarify.

BTW - if the Unions on your UV unit are large enough and easily accessible, I wouldn't bother adding yet more unions ... but that's a personal choice. I like to use as few glue joints as possible in my plumbing to reduce the number of things that can go wrong - and add unions only where necessary to allow me to remove equipment easily.
 
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rickster

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You need to put one check valve on each line that has a direct path from the display tank to the return pump discharge.

So ... if I understood your original posting correctly, it sounds like there is a single line coming from your return pump that connects to the inlet of your UV, and then the outlet of your UV connects to a "T" fitting, from where your return splits into two separate return nozzles inside your display tank. If I got this right, I would simply place ONE check valve between the discharge of your UV and the "T" fitting.

You can of course put one check valve on each return nozzle (i.e. between the T fitting and the nozzle itself), but this is just adding work in my view.

If I didn't understand your plumbing arrangement correctly, please clarify.

BTW - if the Unions on your UV unit are large enough and easily accessible, I wouldn't bother adding yet more unions ... but that's a personal choice. I like to use as few glue joints as possible in my plumbing to reduce the number of things that can go wrong - and add unions only where necessary to allow me to remove equipment easily.
I'm putting a T right after the check valve to have one go into the UV with a ball valve to control that flow and then going into one of the returns and the other pipe off that T going into the 2nd return outlet ( full pump speed ).
does that make sense to do?
 

theMeat

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If you have two drains you should run Herbie style drain, and in that case they shouldn’t be t’d together. Any check valve in time will get crud and not work. Drill a small siphon break hole on return line just below water surface. Simulates power outage to see how much water falls to sump to determine your sump’s max fill line to avoid a flood
 
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rickster

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If you have two drains you should run Herbie style drain, and in that case they shouldn’t be t’d together. Any check valve in time will get crud and not work. Drill a small siphon break hole on return line just below water surface. Simulates power outage to see how much water falls to sump to determine your sump’s max fill line to avoid a flood
yes, I will run the herbie, I wish it had three holes so I could do the bean animal , but my concern is on the return
 

theMeat

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yes, I will run the herbie, I wish it had three holes so I could do the bean animal , but my concern is on the return
Cool. Like said you should drill a small hole on each return just below water level in tank. This hole will break the siphon and is fail safe. Unlike a check valve which will get crud and not seal. Do both siphon break and check valve if you like. Just don’t put your trust in the the check valve, of any kind. It will work great at first, then it won’t
 

TexanCanuck

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I'm putting a T right after the check valve to have one go into the UV with a ball valve to control that flow and then going into one of the returns and the other pipe off that T going into the 2nd return outlet ( full pump speed ).
does that make sense to do?
No ... that won't give you the flow rate through the UV you are looking for.

The water after the "T" is going to follow the path of least resistance ... on the one side, it will encounter the ball valve followed by the UV followed by the return nozzle (all of which add resistance to flow) ... on the other side, it will only encounter a return nozzle (which has much less resistance to flow) ... as a result, the water is going to follow the SECOND branch and you won't get much flow at all through the UV.

The good news here is that the UV will function really well to sterilize parasites! Then again, without enough flow rate through the UV you won't get enough turnover to deal with Algae.

Put the ball valve on the side of the "T" that only goes to the return nozzle, and then throttle it down until you get the flow rate you want through the UV (this is the critical parameter you need to control).

NOTE: To improve your plumbing, don't use a ball valve to throttle the flow (they really don't work well for this function) ... use a GATE valve instead ... like this:

 

TexanCanuck

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One other thought to keep in mind as you plan this tank ... all of the plumbing you are contemplating relies on a single return pump from the sump to the display. This is very typical, but keep in mind that one device becomes a "single point of failure" for your whole tank. If it dies, not only does your UV not work, but neither does your mechanical filtration, skimmer, heaters, carbon reactors, refugium, or any other piece of equipment you have in your sump.

There is another way to do this that will absolutely ensure you get the flow rate you want through the UV AND will give you better fail-safe redundancy ... but it is definitely a little more expensive.

Simply use TWO return pumps from the sump, and have one pass through your UV on the way to one return nozzle while the other pump simply goes straight to the other return nozzle. (and YES, put check valves on each line).

The pumps do not need to be the same size ... and naturally, you will need to buy smaller pumps.

This has a few advantages:

1) you will get exactly the flow rate you want through the UV without having to throttle it through a valve, or worry about the water following a different path through your plumbing. In fact, you can "tune" the flow rate through the UV to exactly the right rate you need for your application (example ... flow rate for sterilizing algae is different that flow rate for sterilizing parasites and bacteria) by either carefully choosing the right pump or by using a variable speed pump.

2) you will have redundancy ... if one pump fails, you will still have water flowing through your sump (and therefore filtration, skimmers, heaters, etc.) ... albeit at a slower rate. This buys you time to fix the problem unit

3) Your plumbing is greatly simplified

Of course the disadvantage is that you need to have enough room in the sump to accommodate both pumps, and you will need to use both of the return lines drilled through your tank.

Anyway ... not a solution for everyone, but something to consider.

Here's what mine looks like ... 2 variable speed return pumps flowing through 2 separate UV units before going back to the tank ... and the flow rate through each one is tuned differently to accommodate a different task (one for algae, one for parasites). I also added flow meters to help my fine tune the pump speeds. My check valves are installed on each return line immediately before they go into the tank.

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