Marineland 300dd drain question

[AriMiko43]

Does anyone know approx. how many gallons drain from the DT when the pump is shut off?

[hobbzz]

It would depend on your plumbing setup. It would be different for each tank.

[ca1ore]

Well, tank is 72" x 36", so each inch of water height in the tank is approximately 11 gallons. Unless you are planning to run a really big pump, water level will rise by less than an inch with the main pump running, so when turned off, you will see somewhere between 5 and 10 gallons drain into the sump.

[AriMiko43]

Ok because I am using a 80g frag tank as a sump with a 8" water height which leaves me another 6 1/2" of water drain area. I just want to make sure the sump is enough to hold the drain water. I plan on putting a check valve on the return from the pump. You really think it only drains 1" down? I calculated 2" of drain to be almost 22 gallons which will fit in the sump no problem. Thank you

[SloppyJ]

I wouldn't go with a check valve. You need your sump to handle all of the water without one.

[ChrisKirkland]

When the pumps are off mine will drain about 15-20 gallons of water after pumps are off.

[albano]

The difference would be how low the returns are in the DT , because they will back flow until they suck air
IME check valves do not work

[ca1ore]

Originally Posted by AriMiko43

You really think it only drains 1" down? I calculated 2" of drain to be almost 22 gallons which will fit in the sump no problem. Thank you

Well, the amount of water that will drain down will be that which rises above the top of the weir once the pump is running. I'm not home to measure mine, but I doubt its even one inch. Like Albano says, back-siphon from the return could be an issue, so just make sure that you have siphon breaks near the surface of the tank (or even better inside the overflow).

[azjohnny]

I think its a good idea to do a "power outage test"disconnect the power and see how much water drains. I do have a George Fisher Wye check valve that I have confidence it. I have it installed with a double union ball valve at each end so it can be removed disassembled and cleaned

http://www.bulkreefsupply.com/georg-...eck-valve.html

[mypepper]

Originally Posted by azjohnny

I think its a good idea to do a "power outage test"disconnect the power and see how much water drains. I do have a George Fisher Wye check valve that I have confidence it. I have it installed with a double union check valve at each end so it can be removed disassembled and cleaned

http://www.bulkreefsupply.com/georg-...eck-valve.html

I have the very same valve for my 90 gallon reef tank and works like a charm.

Randy

[albano]

Originally Posted by azjohnny

I do have a George Fisher Wye check valve that I have confidence it. I have it installed with a double union check valve at each end so it can be removed disassembled and cleaned

have you done the 'power outrage test', recently?... I don't understand why you would need to remove it to clean it?

I have a couple that I had used on my system in the past, and they were basically useless

[azjohnny]

I don't understand why you would need to remove it to clean it?

IME all equipment in our hobbly should be cleaned every 6 months or so, its preventive maintenance. You do get a buildup of slimey crap that at the wrong time would prevent the check valve from operating. I do think that is the reason some reefers have had check valves fail in the past

[azjohnny]

have you done the 'power outrage test', recently?.

Pretty much everytime I do a WC I am doing the test, I turn of the return pump, let all of the water drain into the sump and change out all of the water in the sump.

[ca1ore]

Originally Posted by azjohnny

Pretty much everytime I do a WC I am doing the test, I turn of the return pump, let all of the water drain into the sump and change out all of the water in the sump.

Except that's not really an effective power-outage test. The problem with check valves is not that they don't observably work but that they don't seat properly if allowed to get any kind of dirt buildup (which can happen in days). So, turning the pump of briefly, observing that the check valve 'works like a charm' and allowing the tank to drain to the tops of your overflows only proves that you'd be good in the event of a brief power-outage. You are likely still getting a slight leak through the check valve that, over a longer period of time (say overnight) may well overflow the sump.

It is wise, therefore, to have a siphon break on the return pipe - and if you are going to do that, it makes the check valve redundant.

[albano]

Originally Posted by azjohnny

IME all equipment in our hobbly should be cleaned every 6 months or so, its preventive maintenance.

The question was not why to clean it... But why do you need to REMOVE it, to clean it?...(the cap comes off, and the 'float/stopper' can be removed, without disassembling the PVC piping)

Originally Posted by ca1ore

Except that's not really an effective power-outage test. The problem with check valves is not that they don't observably work but that they don't seat properly if allowed to get any kind of dirt buildup (which can happen in days). So, turning the pump of briefly, observing that the check valve 'works like a charm' and allowing the tank to drain to the tops of your overflows only proves that you'd be good in the event of a brief power-outage. You are likely still getting a slight leak through the check valve that, over a longer period of time (say overnight) may well overflow the sump...

Exactly... It seems that, when there is not enough water pressure on the 'closed' check value, they will have a slow, continuous leak back

[azjohnny]

The question was not why to clean it... But why do you need to REMOVE it, to clean it?...(the cap comes off, and the 'float/stopper' can be removed, without disassembling the PVC piping)

When I design the piping I think ahead and plan on having to remove/disconnect for cleaning. IMO the cleaning is easier if you can remove and not have to have your head below the tank and in the sump. I clean not just the angled section but also the input and output.

Exactly... It seems that, when there is not enough water pressure on the 'closed' check value, they will have a slow, continuous leak back

So far this hasn't been an issue, that will happen with the flapper types, with he George Fisher Wye design the stopper is pretty heavy. When I installed the check valve I was more concerned if my return pump would be powerful enough to lift the stopper

[ca1ore]

Originally Posted by azjohnny

So far this hasn't been an issue, that will happen with the flapper types, with he George Fisher Wye design the stopper is pretty heavy. When I installed the check valve I was more concerned if my return pump would be powerful enough to lift the stopper

I used GF+ Y check valves for years and they all leaked - but maybe you are better at routine maintenance than I am. Regardless, I'd not recommend them to anyone new to the hobby. The other issue, implied in your comment, is that these things unnecessarily rob your pump of flow due to head pressure. Really pointless IME.

[AriMiko43]

Thank you for the info guys. I adjusted the height of my water level in the sump to run at 8" high which my swc 230 skimmer runs great in. This now leaves me with almost 30 gallons for drainage. I'm sure I have enough space now. I am not using the check valve anymore.