Emergency Overflow... Too low?

[Gangrene]

So, I'm setting up my new 75 gallon display... This is my first tank with a overflow. I've decided to go with a herbie style overflow as there are two drilled holes in the tank. The comfort of having a emergency drain seems too beneficial to do otherwise. The inflow will go over the back.

So, I'm building all my own plumbing for this build. I measured everything, some parts being threaded and some parts using cement with smooth connections. Well, when I started to the final assembly I applied the teflon tape to the 3 threaded connections and across the three of them I was able to screw them in about a inch more than I had them without. Now the emergency drain is lower than planned and I'm pretty sure this will cause the sump to be lower or the emergency drain to be over used making the lower drain less functional.

So, the question is... will this extra inch of "waterfall" in the overflow result in a lot of noise and should I re-cut some parts or will this on the other hand be completely unnoticeable? Anyone have overflows with a similar height difference between their display and the overflow?

Take a look at what I'm seeing...

https://imgur.com/a/76M1UEQ

I'm really interested in some feedback from people who have done stuff like this before or have a similar overflow water height.

FYI, both drains, the main and the emergency, have those strainers on top. I have a lot of inverts and they're there just in case, for their protection.

 

[tmnails]

I would move it up a little bit. You want the emergency to start draining just above your intended water level, which is gonna be in the middle of the weir teeth.

 

[laverda]

As long as it is a little higher than your main drain your ok. Teflon tape is not recommended for PVC pipe fittings. it lets you over tighten them causing them to possibly split. Teflon past is the proper thing to use for PVC pipe threads. it will still seal if you have to loosen a joint a little for alignment purposes. In this case, you could just back the screen out a little to make it taller. With Teflon tape, you can not usually do that and expect it to seal. In the case of your drain lines inside the overflow, there is no real reason to use either.

 

[mcgyvr]

That looks awful restrictive..
I'd run without that strainer for sure.. You already have teeth on the overflow box..
Just use pvc pipe and nothing else..

And yes.. Teflon tape is for metal.. Non-hardening thread sealant specifically intended for PVC is what should be used.. Rectorseal,etc...

 

[Gangrene]

Teflon tape is not recommended for PVC pipe fittings. it lets you over tighten them causing them to possibly split.

...

In the case of your drain lines inside the overflow, there is no real reason to use either.

Yeah, I hear your concerns about the splitting and it is a real issue, but the fact is the Plastic Pipe and Fittings Association recommends using PTFE thread tape. If you want more details on that check out this video on YouTube... https://www.youtube.com/watch?v=J2GYmyVwUy4

Yeah both drains go straight down into the sump and are only gravity fed so I'm thinking I really don't need to cement or tape at all as all I'm really looking at is a possible slow leak of my overflow down into my sump Which probably isn't a big deal, but I'm going to test that to find out. Maybe I will end up backing out those threads. Time and testing will tell.

 

[Gangrene]

Teflon tape is for metal.. Non-hardening thread sealant specifically intended for PVC is what should be used.. Rectorseal,etc...

As I noted above with the thread tape... "I hear your concerns about the splitting and it is a real issue, but the fact is the Plastic Pipe and Fittings Association recommends using PTFE thread tape."

I just pulled this quote from the PPFA website:

What type of thread sealant should I use on threaded plastic fittings?

You are always safe to use PTFE Teflon tape (3 mil thickness). If a specific fittings manufacturer recommends a specific brand of thread sealant then it is acceptable to use it on their fittings only. There are many different types of thread sealants on the market and even though some may say they are acceptable for use with plastic fittings they may not actually be chemically compatible. Even some Teflon paste sealants can cause premature fitting failure due to chemical attack.

Warning - Always follow the fitting manufacturer's recommendations on the type and brand of thread sealant to use!

Again, I'd say this is a valid concern, but I'm going with the PPFA's recommendations... and they warn against using paste as seen above. They say it's, and I stress, ALWAYS SAFE to use PFTE tape... if done properly. As I didn't get specific manufacturer suggested paste with the parts I bought at Lowes and Menards, based on the PPFA suggestions, I'll stick with the tape, not a intended pun... but there it is. ;-)

That looks awful restrictive..
I'd run without that strainer for sure.. You already have teeth on the overflow box..
Just use pvc pipe and nothing else..

So, here's my thought on the strainer. Both of my drains are using the same strainer setup. So, if my main drain, while being restricted with the valve, can handle the complete flow based on my pump to the display... then if the emergency has to take over it should be able to handle the job unrestricted. Seeing as I'm going to be checking the drain frequently to watch for flow restrictions with the main drain strainer I shouldn't have a issue with the emergency flow and the main flow both being restricted to the point where there isn't enough flow across the two of them to handle the pump... but maybe I'm being too optimistic.

I guess my concern, if you're wondering, is a larger snail climbs over the overflow teeth, which should be technically possible, and would go into the unstrained pipe. If it was the right size its shell might catch at the bulkhead where the drilled glass is (a restriction in ID of the pipe and flow). That could give me a major blockage restricting almost the entire flow which would be a disaster. Where, alternatively, if the snail is covering just a part of the strainer with it's foot would only partially restrict the flow, in part, and not be as bad... allowing to the rest of the flow in that pipe and the other pipe to handle the water flow volume. At least that's my thinking anyway...

 

[mcgyvr]

Note the warning to always follow the manufacturers recommendations...
Lasco one of the largest suppliers recommends against teflon tape..The manufacturers recommendations trumps any outside bodies recommendation.
Check with the company that manufactured your fittings for the final word..

We have seen it time and time again here..The majority of threaded pvc failure issues involved teflon tape..

As this is inside the overflow box it really doesnt matter...Just passing along information in hopes the next person avoids tape

 

[Gangrene]

Note the warning to always follow the manufacturers recommendations...
Lasco one of the largest suppliers recommends against teflon tape..The manufacturers recommendations trumps any outside bodies recommendation.
Check with the company that manufactured your fittings for the final word..

We have seen it time and time again here..The majority of threaded pvc failure issues involved teflon tape..

As this is inside the overflow box it really doesnt matter...Just passing along information in hopes the next person avoids tape

Thanks Mcgyvr!

So far I've tested out the pluming, sump, and refugium and everything is working great. I put the return line directly into overflow for testing. I got the main drain valve perfectly adjusted. It probably takes 5-7 minutes to fill the gap between the main drain and the emergency, so the emergency is taking ultra low flow, but some. Even with the strainer the main drain easily takes the whole flow of the return pump. I had to valve it down a good amount. I'm pretty sure the two drains, in concert, will be able to handle what the tank throws at them... and if the emergency takes partial flow the noise is like a alarm bell going off. ;-)

As I'm slowly making RODI water and adding it to the tank I can't wait to see if I'll need to make a longer pipe for the emergency drain. That's the last piece to test and the point of this post. ;-) Just interested to see if the waterfall into the overflow is going to generate noise. The waterfall from the refugium to the return chamber is silent. So, only time will tell. I run RODI as time is available.

 

[bluemoon280]

Errrrmm. Why do u need tape on the joints ? They are inside the drain box. Isn't tape to stop wet to dry leaks??.. or am I missing something...

Sent from my SM-A520F using Tapatalk

 

[Gangrene]

Less drips and salt creep? It would drip into the sump, you're right about that...