Gas build up in sealed wet-dry tower

[camilocastroalvarado]

Hi,
I'm wondering if someone using trickle filter is experiencing gas build up in the sealed wet dry tower; I recently designed a new wet-dry to my 70 Galon aquarium. The basic idea was to make sealing the wet-dry tower simpler, so I decided to take an old 8 galon tank as the tower and invert it, so the botom became the lid. The problem is that there's a noticeable gas build up in the tower that made the tower to burp the first day, the water level in there is actually lower than in the sump. I added a U shaped glass tube and conected it to the NW intake to prune the gas when it starts to build up, but I just don't know if that is the correct way to proceed and bubbles in the tank when it happens are very big, the main pump even stops working for a few seconds.

Also I wonder if that can make CO2 levels to fluctuate in the tank.
Here are some pictures of the system:





A detail of the tower



Gas build up



How I'm pruning it



Link to the video of the filter operating

https://www.facebook.com/photo.php?v=649663655105215&set=vb.326127370792180&type=2&theater

Some photos of the tank 2 weeks ago before I changed the filter:





Thanks for your help.

 

[AaronT]

As long as it is working and relieving the gas then it should be fine.

 

[camilocastroalvarado]

Thank you AaronT but it was a PITA to dial the gas relieving this way, I've just untightened the bulkhead a bit creating a very small leak in the joint, water levels are back to normal but now it isn't airtight anymore. I wonder if Tom and others have their wet dry towers completely sealed.

 

[gsjmia]

I have the same situation, but mine is a 3 foot high, DYI 1/4" acrylic box tower with only the bottom open and it sits in a 20 gal glass tank. Its totally sealed at the top just like yours. I also have a similar bracket to hold the drip plate in place (which has to be changed from the inside-PTIA)

My problem is that it floats when it gets too much gas in it and all my filter foam that normally sits on the bottom gets loose.

it only seems to happen when changing the water. Otherwise it doesn't happen. But, if don't burp the air out the siphon won't work right because of the back pressure.

I have a 1-1/2" pvc 90 where you have your barbed fitting. At the top of the 90, I drilled a hole and put some aquarium airline tubing in the hole with a small air valve attached. When the water is being drained, i open it and it sucks air in. when I fill the tank, I open it to bleed the air out. When the water is at normal level, I close the valve and have no other problems. By drilling a hole into the fitting, you can replace the fitting if you don't like it and won't have hole in your top piece.

I plan to build another wet/dry with a separate compartment in the front for the water to dump into, and then a weir system it will have to go through over the top to get into the drip box, with a 1/4" overlap so the water can be burped in or out yet still be sealed.

What size is your barbed fitting (is it 1"?), it doesn't look big enough to handle much flow. If its not 1" you may need to increase, depending on your GPH. Is this drain line running as a full siphon? If not it will be sucking air (literally ) and transporting the air bubbles into your wet/dry and causing it to fill up with gas/air.

In your drip tray, it looks like you have dacron or some other filter material, which must be a pain to change or clean. I was getting a lot of splashing noise in my drip box, and I filled it with bio-bale. No noise and it doesn' clog. I pre-filter my water with a round sponge filter over the over flow box siphon drain, which catches the solids.

Honestly, I don't know if having a sealed top is worth all the hassle. Others don't have it and it doesn't seem to matter. This is my first wet/dry, so I don't know. Other than that Mrs. Lincoln, its a great filter.

 

[camilocastroalvarado]

Hi gsjmia, thanks for replying.

What size is your barbed fitting (is it 1"?), it doesn't look big enough to handle much flow. If its not 1" you may need to increase, depending on your GPH. Is this drain line running as a full siphon? If not it will be sucking air (literally ) and transporting the air bubbles into your wet/dry and causing it to fill up with gas/air.

That is a 1" barbed fitting, it's a full siphon. There's actually another 2 drains in the overflow but they are draining in the sump area. I took the Beananimal design for this.

In your drip tray, it looks like you have dacron or some other filter material, which must be a pain to change or clean. I was getting a lot of splashing noise in my drip box, and I filled it with bio-bale. No noise and it doesn' clog. I pre-filter my water with a round sponge filter over the over flow box siphon drain, which catches the solids.

It appears to be dificult, but it's not. When the drip plate needs to be cleaned, I remove the tower and take the bioballs out first, then the drip plate. Same thing to reassembly it. I use a sponge prefilter in the full siphon intake and clean it twice a week. It's in the overflow box so it's easy. About the noise, I can't hear anything but the pumps, there's very little splashing in the entire system.

It seems to be logical that if the entire tower is sealed and no burps are comming out of the intake, gases acumulates there. I wonder having it completely sealed is necessary, if gas tends to acumulate, there will be a moment in wich it will burp and will continue doing it over the day. If I purge it, the same situation. That's like having a leak and the system will be unstable untill it starts lo relieve the gas. I remember reading George Booth observations and according to him, the tower wasn't completely sealed.

 

[gsjmia]

It seems to be logical that if the entire tower is sealed and no burps are comming out of the intake, gases acumulates there.

If its a full siphon, I don't see how you would be getting additional gas build up, especialy if you have a filter sponge.

I don't get gas build up when its running, only when the water level changes during water changes. I have a P-trap type loop in my siphon hose to keep the drain hose air tight, maybe that causes any gas to revert to the overflow instead of passing to the wet/dry.

- - - Updated - - -

It seems to be logical that if the entire tower is sealed and no burps are coming out of the intake, gases accumulates there.

If its a full siphon, I don't see how you would be getting additional gas build up, especially if you have a filter sponge.

I don't get gas build up when its running, only when the water level changes during water changes. I have a P-trap type loop in my siphon hose to keep the drain hose air tight, maybe that causes any gas to revert to the overflow instead of passing to the wet/dry.

 

[camilocastroalvarado]

Hi,

You made me realize of something. I was thinking that the gas accumulation was because of CO2 degassing, but perhaps I'm wrong. I haven't checked the threatened conections of the valve coming out of the overflow box, I assumed that they're right because there are no water leaks, but with the system running, a bad conection there can cause the drain to suck little amounts of air instead of throwing water. I'll go with glued slip fittings tomorrow and willl let you know if that solved the problem.

Thank you very much for your help.

 

[Ach1Ll3sH33L]

I experienced the same thing, i believe its mostly air that gets pulled down with the water from the overflow, gravity tends to pull both when relying on only one drain. You can mitigate this by using multiple drains in the overflow box, make sure the drain going to the filter portion of the sump is full siphon at all times(it wont pull air), then use the other drain so water just trickles down it and goes into the return pump side. You can use a gate valve on the main drain to fine tune the flow.

 

[gsjmia]

I think he has the standard 3 drains, but the it looks like the #2 secondary overflow drain is the other 1" braided vinyl hose in the picture that seems to be dumping out right into the pump intake. That hose will always have air bubbles (depending on the volume of flow) and should be placed on the other side of the sump so the pump doesn't grab those bubbles-you could even build a foam dam to keep the bubbles away from the pump intake.

If the pump is grabbing those bubbles, then that is what is filling the tank with bubbles, and those bubbles may even be persistant enough to make the round trip back through the overflow and then add gas to the sealed filter.

 

[camilocastroalvarado]

Hi,
As gsjmia said, I have 3 drains (full siphon, half siphon and emergency drain), the half siphon drain is gently trickling far away from the main return pump.

I've been working in the filter and redid the threaded conections of the full siphon drain, I also changed the valve and sealed the bulkhead in the tower again. Noticed some things:

1. Gas accumulation was greatly reduced by 1 inch at the end of the light period (previous excessive gas accumulation could be caused by a bad connection).
2. Gas accumulation doesn't occur at night, which can suggest it's due to CO2 outgassing in the wet-dry chamber.
3. Noticed fish stress when gas built up.

I added a small air hose that comes from the top of the wet-dry tower to purge gas when changing water, it bassically matches the water level in the chamber with the sump's. I tried to leave that hose submerged when the filter is running so no air scapes from the wet-dry, but gas build up causes a little back pressure and the flow of the full siphon drain was reduced and lead to water level variations on the outside overflow box. Because we're looking for stability, I decided to leave the hose out of the water so the levels of water in the wet-dry tower, the sump and the overflow box matched all the time. Increased the CO2 a little and I can notice a little fish stress, which can suggest that degassing isn't occuring that fast. Things will be more conlusive if I had a Ph meter on hand, but I don't.

I made a short video of the system working showing the tank, flow and other things, I really appreciate any suggestion you have.

[video=youtube_share;wxybj3wXU-4]http://youtu.be/wxybj3wXU-4[/video]

Regards.

 

[gsjmia]

Two things, and I do both of these and ceased experimenting:

1. Just my opinion, but you have way too many bubbles and you must be losing a lot of co2-many float to top and get out without dissolving. It looks like you are using an atomizer (but you are not). Is that tall blue filter thing your cerges style Co2 reactor? If so, I would take it out of the return line, get a second (smaller) pump and pull from the sump like you are doing but return it back to the sump at the other end from the return pump, with foam in between to filter the bubbles. Also, i would stuff that blue thing tight with Bio Bale. Or whatever else you need to do to eliminate the micro bubbles. Look at 3:17 in your video, you can see the bubbles heading for the overflow. Those bubbles could be causing all if not most of your remaining 1" difference.

2. In your drip tray, you have a ton of turbulence, it must be noisy plus I would think that much turbulence would knock the co2 out of the water. I would also stuff the drip tray with Bio Bale to act as a cushion.

Bio Bale is good for both applications because it doesn't get very dirty and doesn't require cleaning, plus it has a lot of surface area.

My drip tray used to be noisy, but with the Bio Bale it is now silent (I'm sure its also relative to your flow volume).

- - - Updated - - -

Two things, and I do both of these and ceased experimenting:

1. Just my opinion, but you have way too many bubbles and you must be losing a lot of co2-many float to top and get out without dissolving. It looks like you are using an atomizer (but you are not). Is that tall blue filter thing your cerges style Co2 reactor? If so, I would take it out of the return line, get a second (smaller) pump and pull from the sump like you are doing but return it back to the sump at the other end from the return pump, with foam in between to filter the bubbles. Also, i would stuff that blue thing tight with Bio Bale. Or whatever else you need to do to eliminate the micro bubbles. Look at 3:17 in your video, you can see the bubbles heading for the overflow. Those bubbles could be causing all if not most of your remaining 1" difference.

2. In your drip tray, you have a ton of turbulence, it must be noisy plus I would think that much turbulence would knock the co2 out of the water. I would also stuff the drip tray with Bio Bale to act as a cushion.

Bio Bale is good for both applications because it doesn't get very dirty and doesn't require cleaning, plus it has a lot of surface area.

My drip tray used to be noisy, but with the Bio Bale it is now silent (I'm sure its also relative to your flow volume).

 

[bettatail]

your mail box is full, camilocastroalvarado

 

[Ach1Ll3sH33L]

Everything looks fine to me to be honest, the only thing i feel you could improve on is the amount of splashing in the drip tray, the more splashing- the more degassing. I assume the water is building up in that spot because your using a very fine filter pad. These fine pads work well for a few days, then the water tends to just splash over and around them as they build up a gunky layer on top. I would use a more course filter pad, throw in the fine mesh stuff after you uproot a bunch for a few days then remove it. Do you have the ph measurements for your co2 cycle?

 

[camilocastroalvarado]

Hi, I'm sorry I didn't post earlier.

I took your advice and reduced the turbulence in the drip tray. I added a piece of pvc in order to submerge the main drain and put some bioballs in there. As you can see in the video, splashing is much less now. Filter pads are no longer in the drip tray. It's been working for 2 days, I'll let you know how it goes.

Click on the image to open the video:



Bettatail, I already cleared the Inbox, sorry about that.

Thanks for your help
Best regards.