Return line/Drain line issue.. help please!

[AmatuerAuer]

I have a Mag 9.5 on my 120g with roughly 3' of head running through spaflex return line. It is the typical overflow with oversized lines after the bulkhead (1.5"). Lately, return has been draining faster than a full bore return pump line has been able to fill it.

It is not drastic, I'm not getting pooling in my sump or anything, but the tank water level is low enough that the water coming out of the siphon break hole on the return (prior to the lock line) is making an annoying gushing noise that I want to get rid of.

I started closing the return line to keep a higher water level in the tank but I KNOW that is a big mistake and mess waiting to happen.

So what the heck am I on here for right? Here is my question, I plan to replace my Mag 9.5 with a more powerful return pump. The idea being, my return pump can pump more water INTO the tank than the return line can drain FROM the tank when opened all the way.

That way, I can have a fully opened return line (as God intended) and I can dial back the return pump to control the flow.

Looking at the Mag 18, thoughts comments concerns?

 

[mfinn]

I'm assuming you mean that you are valving down the drain line.

If the water level is too low in the tank, raise the height of the drain line, or overflow box.
No need to go with a bigger pump

 

[redfishbluefish]

I'm a little confused. Are you saying the level in the overflow is getting sucked down low. If so, I believe you've started a siphon, and the drain is quickly drawing the water down into the sump. You didn't mention the setup in the overflow, but if it's a durso, clean the little hole in the top of the plumbing. If and when that gets clogged, it causes the drain to siphon.

If I'm totally off-base, please disregard.

 

[AZDesertRat]

The return pump should determine the level in the display, not the overflow which should be un restricted. If you need to raise the display level you will need to raise the standpipe or the overflow box weir height and not restrict the overflow which with a single overflow is a flood waiting to happen. The overflow should always be able to drain faster than the return pump for safety reasons.
I would also get rid of any drilled holes in the return as they are a false sense of security. As long as the return is placed only slightly below the surface and you have sufficient freeboard or spare room in your sump flooding is never an issue. Once power goes off and the level drops and inch or whatever you determine is safe, the return is exposed to atmosphere and the siphon breaks. This is the best form of backflow prevention known to man and cannot be defeated since we all know water cannot jump uphill. No check valves or drilled holes to clean or fail and no maintenance necessary.

 

[AmatuerAuer]

Firstly thank you AZ, RFBF and mfinn for the quick responses.

AZ has the right of it I believe. Let me try to rephrase more cleanly.. Here are the 'rules':
1) My durso drain line should be completely open and unrestricted
2) The DT water level should be controlled by opening and closing the valve on the return pump

Here is the reality today:
1) The drain line is not open fully.
2) The return pump is open fully.
3) The PVC pipe that extends up from the bulkhead in the overflow compartment (the return) has a small hole at the 90 degree neck to stop siphoning in the even of a power outage.
4) The water level in the overflow compartment (behind the black plastic wall, where the durso and return pipes are located) is just low enough that the water being pumped into the DT makes noise as it leaves that hole. That noise is a result of air mixing with the water as it enters that over flow area.

Solutions (from what I am hearing):
1) Swab the durso, specifically the small plastic tube that extends from the top. It should be mentioned, the durso has a 1/2" hole drilled in the side of the neck to avoid a siphon. This is out of the box All Glass corner over flow reef ready build
2) Replace the return pump (currently Mag 9.5) with something more powerful. The result of which would be the ability to fully open the drain and compensate for the increased drainage with an equal and even more powerful filling power from the new pump.
3) Dial back the return pump to a required level.


Sorry for the analytic response..its my brain and I want to be 100% clear.

Thank you!!

 

[mfinn]

The water level in the display tank will be determined by the height of the drain, and or overflow box, not the size of the pump, ( within reason)
As long as the size of the drain is capable of handling the amount of flow.


As long as the drain is the correct height, the water level will be the same if a mag 5 is used or a mag 9.5 is used.

 

[mfinn]

Raise the point of where the water level leaves the tank and the water level goes up.
Lower the point at which the water level leaves the tank and the water level in the tank goes down.

 

[AmatuerAuer]

That makes sense mfinn. Leads to two questions though:

1) It would seem to me that it would be easier to take a small bit of airline tubing (1" tops) and insert it into the return line hole in question and point it down into the overflow. That way, the water leaving the hole would not make noise and it would still be able to function as a siphon break just at a slightly lower level but still within acceptable ranges..

If that is not doable/advisable..

2)What is the best way to adjust the height of an existing drain line on a full tank... that sounds like a leaky bulkhead waiting to happen...

 

[mfinn]

That makes sense mfinn. Leads to two questions though:

1) It would seem to me that it would be easier to take a small bit of airline tubing (1" tops) and insert it into the return line hole in question and point it down into the overflow. That way, the water leaving the hole would not make noise and it would still be able to function as a siphon break just at a slightly lower level but still within acceptable ranges..

If that is not doable/advisable..

2)What is the best way to adjust the height of an existing drain line on a full tank... that sounds like a leaky bulkhead waiting to happen...

The best way to deal with water returning to the sump during a power outage or just turning off the pump is to position the return line high enough in the tank so that the sump can handle the amount of water that drains.
Unless you do that you run the risk of having a disaster. No other way to get around that.

Pictures sure would help show us what you are dealing with.

 

[mfinn]

That makes sense mfinn. Leads to two questions though:

1) It would seem to me that it would be easier to take a small bit of airline tubing (1" tops) and insert it into the return line hole in question and point it down into the overflow. That way, the water leaving the hole would not make noise and it would still be able to function as a siphon break just at a slightly lower level but still within acceptable ranges..
..

I remember someone talking about that method. Wasn't something I wanted to explore so I really didn't give much thought to it.
It would stop a snail from plugging up the hole, but might not stop algae from growing in the tube or at the end of the tube and plugging.
Also may form salt creep and plug.

 

[AmatuerAuer]

I think I found the culprit. You can see the drain (left) is slightly lower than the return. The water level in the overflow is lower as a result.

 

[AmatuerAuer]

I would need to lower the return or raise the drain... Not something I'm excited about doing in a full tank...

 

[mfinn]

, but the tank water level is low enough that the water coming out of the siphon break hole on the return (prior to the lock line) is making an annoying gushing noise that I want to get rid of.

In this case, I would raise the loc line higher in the tank. Enough so that when the power goes out, the sump will handle the amount of water that returns to the sump.
Plug the hole.

 

[AmatuerAuer]

1)

2) Wouldn't it suffice to have the end/just a partial exposure of one of the two line ends? Basically if any point breaks the surface it would break a siphon.

 

[AZDesertRat]

Get rid of the drilled hole. As I said before it is not needed if your overflow and return are designed properly and your sump is sized properly.
I would scrap the durso style standpipe and construct a simple DIY Stockman standpipe with a piece of airline installed in the cap then make sure the return is at the proper submerged depth so flooding is not an issue. You will have a quieter and more reliable system.

 

[AmatuerAuer]

Replaced the 90 elbow, no more hole and. No more return noise. Tested the siphon amount as well, and all clear.

Now the fully opened first gargles. I'll look into the stockman. Replacing the 90 caused a bulkhead leak which was not fun. Salt creep has almost closed it. Should be fine.

Replacing the first would almost absolutely be worse so I will save that for another day, once the reading is done.

Thank you both!

 

[AmatuerAuer]

Durso* autocorrect...