loud drain to sump (air bubbles), how to quiet?

[nunofs]

Just to clarify, Nuno... that's the thread that describes the submerged drain idea, correct? Not the bubble trap that I'm describing.

That's right, it's the one I had mentioned earlier in this thread, when I posted a diagram about the submerged drain. I couldn't find the link at that time, that's why I only posted it now, when we had already moved on to another topic (your bubble trap suggestions).

Nuno

 

[dedfish]

I'm gonna try this:

The T is an 1 1/2" with 1" reducers. About 3 1/2 feet of vertical drop and the return pump is a mag5. Dual 1" drains. What do you think? I won't get a chance to test it tonight.

 

[NateHanson]

I'd make the vent the same diameter as the Tee, otherwise I think the bubbles will push water out of the top of the vent.

 

[dedfish]

Yea...maybe when I get a chance to go to Lowes, they sell 4 or 5 foot sections. I just couldn't justify buying a 8 foot section. None of the bottom pieces are glued. Thanks for the input!

 

[reefnroll]

That's it dedfish!

But exactly as Nate says...
The vent tube needs to be the same diameter as the T, at least for 12" or so... otherwise the water will rise up the tube rather than just the breaking bubbles. You can reduce it after a foot or so... coming out of the water. I did just that (capped with a valve at the top) and it works well, without needing to have a giant vent tube coming way out of the water.

Again... depending on how much force is behind the water in your system... coming into the sump, you may need to upgrade that 1.5" T and vent to a 2"... or in my case a 3" combination before the bubbles and noise disappear altogether.

I also extended my trap about 2" from the bottom of the T to create a slightly larger chamber for the bubbles and water to go their separate ways. Fewer bubbles make it out of the bottom that way.

b

 

[JBendel]

Hello Nuno,

Seems like ReefnRoll has it figured out. My only point is that as water flows into the sump ... Air should have an unimpeded route out, and horizontal runs effect the air flow out ... I had a "gurgling ... gulping" sound out of the water flow until I removed a horizontal run with a 45 degree rise.

I don't have a durso or tank overflow, but just pvc out the side of the tank, and down into the sump.

 

[nunofs]

So I tried Bec's suggestion, and went with a larger diameter pipe and T, 1.5" instead of 1", as Lam had mentioned that using a same-sized T wouldn't work. The setup is identical to what dedfish posted above, only it's all with 1.5" PVC, no reducers.

Unfortunately, it didn't work... I'm still getting lots of air bubbles, only much smaller than before... here's a pic of the 1.5" T in action:

I tried all sorts of different things, like having the T lower/higher in the water, using longer/shorter pieces of pipe, cutting some slits at the bottom of the pipe, etc... still getting bubbles that look and sound like the "fizz" in a shaken soda bottle.

Tomorrow I will build a new version, this time with 3" PVC (decided to skip the 2" PVC to save a step )... I was eyeing the 4" PVC at HD but that won't fit in my sump... hopefully the 3" will work, the bubbling and all the salt creep it causes (even with that area of the sump partly covered) is really getting on my nerves...

Nuno

 

[dedfish]

Geez...that stinks. How big is your return pump?

 

[nunofs]

I'm using a Mag 9.5 throttled back with a ball valve... I'd say it's about half-way open right now. If I open it completely, the amount of bubbles increases a lot, almost looks like the water in the sump is boiling... on the other hand, there is a point when it's almost closed all the way, at which there are just a few tiny bubbles coming out of the pipe, but there's basically no flow at all so that's not really a solution.

Nuno

 

[JBendel]

To produce bubbles like that ... somewhere air is getting mixed with the water ... As water goes down the sump .... air should be escaping out of the vents ... if you check the vents (input and out) .... is the air flowing out as you would expect? A second approach is to cover a vent with your hand, and see if the water/air flow changes as you would expect. ... other than that ... you may have created a new type of protein skimmer.

Apologies on the joke ... took me months to get a sump working at a good flow at work ... the sump was below the tank, but 3 feet offset. Luckily the person on the other side of the partition took enough interest in the project that she put up with the noise.

 

[reefnroll]

Nuno -
A 1.5" T and vent pipe in this bubble trap system is the very smallest possibility to cure a bubble problem... the very smallest - certainly not the end of the road. Your problem is solvable with a little more experimentation. You need to increase the sizes of those two fittings, and put the T closer to the bottom of the sump. Right now your T is up at the water line. 2" or 3" T and vent, since you've obvioulsy got some crazy air in that line. The air has got to be picking up somewhere as the water overlfows from the reef into the pipe that feeds the sump (and the bubble trap). It really should matter so directly how far open your pump is... feeding the flow in the reef - unless your reef is full of wild microbubbles, which I can't imagine.
Whatever the reason for the air in the line, the bubbles need a larger space to crash and break up before the air floats quietly up through the vent. Right now the 1.5" is too restrictive for the force and the water and bubbles together are still being forced down through the bottom altogether.

Also... did you cap the top of the vent, but leave a very large hole in the top or install a ball valve at the top of the vent? The cap is to quiet down the bubbles, but the hole/valve allows the air to escape slowly from the vent.

Where is this sump, Nuno? Right beneath the tank, or a floor below? Just curious.

bec

 

[nunofs]

JBendel: no apologies needed on the joke, it was funny The vent at the top of the durso pipe in the overflow was pre-made (I got the AGA Megaflow kit). When I cover it with my hand, the water level in the overflow drops very quickly... when I remove my hand, I hear a "hissing" noise from all the air leaving through the hole. So that part seems to be working ok, but I may be missing something obvious...

Bec: right, the 1.5" was my first attempt, I understand that going with a larger diameter pipe will increase the chances of getting this to work right... that's why I decided to skip the 2" size and go directly to 3", should be able to try that tonight.

Regarding the pump flow, the only reason it matters is that if the pump is sending more water up to the main tank, there will also be more water coming down to the sump, as the water level in the tank is fixed at the height of the overflow... so throttling back the pump allows me to reduce the flow to the sump and reduce the amount of bubbles as well. And no, I don't have a tank full of microbubbles

As for the cap in the vent pipe, I tried different things: uncapped, capped with only 2 holes drilled, with 4 holes drilled... all produced pretty much the same amount of bubbles, no difference that I could notice. If I cover it completely with my hand, I do get a lot bigger bubbles coming out from the bottom of the pipe, so it is doing something, just not enough.

The sump is in the stand, under the tank... fwiw, there is about a 1.5 foot horizontal offset from where the water leaves the tank (the drain bulkhead) and the place where the water enters the sump.

I'm going to try the 3" vent pipe tonight and will report back, hopefully with good news

Thanks for all the help and support, guys!

Nuno

 

[reefnroll]

You're on the right track Nuno. Everything you've said/clarifies makes perfect sense... just needs a little more tweaking.

I did the same thing with the vent cap... all the holes, covering and uncovering... trying to see if that made a difference. When the T and vent size are right, the bubbles will disipate, and the size of that hole at the top of the vent will only determine whether the air leaving it whistles (too small) or seeps out almost silently. For me - the hole is about 3/8".

FYI - HD sells 3" Ts that are 3"x3"x1.5" The 1.5" end is slightly curved. Position that curved end of the T facing the water's surface, and reduce it down to 1" for your feed pipe to fit. Also get a 3" coupling so that you can extend the now 3" vent pipe up for a stretch (6"-8" or so) from the T... to allow space for the accumulating air before it leaves the vent. Then reduce that thing down again and cap it with the same cap you've been using.

Hope that does it. Can't wait to hear the good news.

bec

 

[nunofs]

Bec, that's exactly the T I got at HD last night, along with a 1.5" to 1" reducer to accept my 1" pipe at the intake of the T. Now I only need to go buy a small section of 3" pipe, HD only sells them by 10ft lengths... O'Connors in Billerica has smaller sections (3 or 4ft, I think), in case anyone else is looking for some.

Nuno

 

[reefnroll]

Great Nuno. You're halfway home!

Hey I meant to ask you. Do you have slots cut into the bottom of that tube (the one coming out of the bottom of the T)? It looks like that's the case, but maybe just a strange photo. If so... you'll want to use a different tube that is solid all the way to the bottom. The slots are workign against you. They allow bubbles to escape from the sides of the tube, rather than keeping them inside the tube where they are more likely (once the space is increased by the larger fittings ) to float up and out of the top... the way you want them to. Keep the bottom of your 3" T about 3" from the bottom of the sump, and add a solid tube coming out of the bottom of the T down to the sump floor... even sitting on the bottom of the sump is o.k. as long as it's angled enough for water to slip through.

b

 

[nunofs]

Yes, I did cut some slits on the bottom of the pipe, but only after trying the solid pipe first, touching the bottom of the sump... I thought the water could be building up some pressure inside due to not having a very large opening to exit the pipe at the bottom, so I tried the slits... but, as you just mentioned and as I realized shortly after cutting them , they didn't help at all. I won't be cutting any slits on the 3" pipe for sure.

Nuno

 

[nunofs]

I have good news and bad news...

The good news is that I've just finished putting the 3" T and pipe in place and it does reduce the number and size of bubbles a lot! Not completely, but a lot.

I lowered the T into the water like Bec suggested, put a solid 3" pipe all the way to the bottom of the sump, and another 3" pipe as a vent. The whole thing is leaning just a little bit so that the water can flow freely on the bottom... there are still bubbles coming out, really tiny ones, and I tried all sorts of things...

The bad news is that I cracked a baffle in my sump trying to fit the monstrous 3" T in there It hasn't shattered to pieces, it's just cracked from top to bottom, so I'll leave it as is for now, hopefully it'll will be ok... it's really thin glass (window pane glass), should have used something stronger.

So I decided not to mess with the bubble trap any more... as it is, it's not perfect but it's good enough... my only concern now (besides the baffle) is that the microbubbles from the trap manage to get sucked into the main tank, but for now that's not happening, the baffles are doing their job.

Anyway, thanks again everyone for the suggestions and for helping me get this problem solved once and for all!

Nuno

 

[reefnroll]

Crap! I'm sorry that happened Nuno... really sorry. At least nothing disasterous took place...and it sounds like your bubble issue is greatly reduced.

I'm still perplexed about why the bubbles aren't gone altogether, as they appear to be in my sump. However... I've got a 100 gallon sump, so maybe the extra space makes a difference in the bubbles I can detect. It sure looks clear, and is definitely silent compared to when I began.

Good luck with whatever your next step is, and may it be simpler than this one!

bec

 

[nunofs]

Bec, please don't feel bad about it, you helped so much during this project! I was trying to make the 3" pipe fit between the intake and the output of the skimmer by rotating the skimmer around in my cramped sump, pushed too hard and the skimmer slammed into the baffle, cracking it top to bottom...

I'll take a pic tomorrow showing the bubbles that I'm getting now... but as I said, I'm reasonably happy with how it's working now, and unless it's a really simple/quick change I don't think I'll tweak with it anymore. Btw, it is pretty much silent, there's just a kind of muffled bubbling sound (from the bubbles popping inside the pipe) when I get close. Much, much better than before!

Nuno

 

[nunofs]

As promised, here's a pic of the 3" T in place... if you look closely you should be able to see very tiny bubbles rising around the bottom of the pipe (actually, they're easier to see against the T itself):

Still, it's a huge improvement over what I had before.

Nuno