CO2 Spray Bar

[22802]

Hmmm, thinking about this a bit more. Just how do you make 2 straight 90cm cuts in polycarbonate tube without it cracking, splitting or melting? I have a Dremel, with cutting wheel ... would melt and gum up, diamond wheel ... same, Circular saw .... err just no, Recip saw ... not a frickin' chance! Multi-tool ... vibrating with a fine blade on slow speed, and take it slowly ... Possible ???

This is what I make, 1 inch pipe cut at 180 degrees (recently I prefer 220 degrees to contain the CO2 in a strong flow from the water spray bar). The ends are fully closed, so that the end pieces can be mounted without glue and the tube rotated in the end pieces for alignment.



Drawing straight lines over the full length. I use an aluminium 90 deg profile to hold the tube, and permanent marker:



Then carefully cut with a hand saw. The blade is held nearly parallel to the tube's surface:

 

[Aleman]

Then carefully cut with a hand saw. The blade is held nearly parallel to the tube's surface:

View attachment 191975

The one tool I don't have Oh well, I guess you can never have too many tools 😀 😀
Your design, was pretty much exactly what I was thinking it would be ... I may make a few alterations to fit in with my tank.
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Japanese dozuki pull saw on way 😀

 

[22802]

The one tool I don't have Oh well, I guess you can never have too many tools 😀 😀
Your design, was pretty much exactly what I was thinking it would be ... I may make a few alterations to fit in with my tank.
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Japanese dozuki pull saw on way 😀

If you have questions about the details of the design, always here to help.

Please note that I never use glue, and that by varioius rotation options in the design we are very flexible to experiment with different positions for the CO2 Spray Bar relative to the water spray bar. If this is not clear from the pictures, happy to elaborate.

The most important alignment is that the CO2 Spray Bar is always horizontal. I usually position the top of the CO2 Spray Bar exactly at the tank water surface. When I want to mount it lower, I use a turkey blaster to blow a few bubbles of air in (as in a level tool), and with these bubbles it is also really easy to find the horizontal position.

After maintenance and water change, I usually use a turkey blaster to suck any air from the CO2 Spray Bar. As I illustrated earlier it will purge air automatically, but it is just a bit quicker next morning if an empty bar gets filled with pure CO2 without the need for air purging.

 

[Aleman]

What I love about this design is that it is so simple, which means it's elegant. I'm still trying to solve a lack of flow issue in the tank, due to hardscape, which the spray bar and CO2 spray bar might go some way to solving ... I may also add a small cross flow pump on one end to make sure that there is sufficient flow where needed.

Oddly enough my real question is about the spray bar. I'm still playing around with the number, diameter and pattern of holes. in order to achieve "constant" (or consistent) flow along the length of the bar. Equal Spacing and equal diameter holes along the bar leads to high flow closest to the filter and low flow at the other end. Unequal distribution of the same diameter holes, more, closer together at far end gives the appearance of a consistent water flow. I suspect that smaller holes at the near end and bigger holes at the far end with an equal spacing between would give a similar flow.

This is "obviously" linked to pressure drop along the length of the spray bar. I guess just turning the flow of the filter up will solve my problem, and I can go with larger holes equally spaced.

Of course I could simply be overthinking the whole thing 😀 ... and lets not talk about the floating plants that are going to hate being in a jaccuzzi ... Get rid and turn the light intensity down 😀

 

[22802]

I'm still trying to solve a lack of flow issue in the tank, due to hardscape, which the spray bar and CO2 spray bar might go some way to solving ...

For the CO2 Spray Bar to work well, we need a decent flow. For the full tank stability, where surface agitation is key, flow is even more important (whether a diffuser, reactor or CO2 Spray Bar is used). With the water spray bar over the full back of the tank, driven by a powerful enough (filter) pump most layouts will have a good surface agitation as well as flow within the tank. I would therefore prioritize the flow from the water spray bar, rather than wave makers in the tank.

I'm still playing around with the number, diameter and pattern of holes.

That's also what I do, as I tried but find it hard to theorise what is the best design of holes in the water spray bar. To keep things simple, I calculate the sum of the surface areas of all my holes, and want that to be similar as the crosss section surface area of my filter hose. Then I play with the spacing between holes and see what happens.

When I first tested my latest design (CO2 Spray Bar mounted in front of water spray bar), I was worried about blowing CO2 bubbles out, and chose only 2 cm spacing of holes on my water spray bar. It worked, but it gave me too little surface agitation for my taste, so I went back to the 3 cm spacing that I most often use. This works fine for CO2 Spray bar and some decent flow in the tank (around 5 cm/ sec).

 

[22802]

My current insights on CO2 stability, short term (within the day) as well as long term (day-to-day, week-to-week) using the CO2 Spray Bar in different modes of operation.

Three alternative approaches to using the CO2 Spray Bar:

1. ‘Overflow mode’. We inject slightly more (5%) CO2 in the CO2 Spray Bar than the CO2 absorption into the water. The CO2 reservoir remains always full, and every few minutes we see an excess CO2 bubble escape from the CO2 overflow.
2. ‘Regulator mode’. We use the CO2 Spray Bar below its capacity, so that the CO2 meniscus never reaches the overflow and no CO2 bubbles escape from the overflow. It is now the setting of the CO2 regulator that drives how much CO2 is absorbed in the tank.
3. ‘CO2/pH controller mode’. As Regulator Mode, no bubbles escaping from overflow, but rather than the regulator it is the CO2/pH controller that drives the CO2 injection rate.

Some general remarks on CO2 stability in tank (no CO2/pH controller)

• CO2 ppm stabilises when CO2 injection = CO2 surface outgassing + plant CO2 uptake. For a good CO2 stabilisation in the tank it is essential that CO2 outgassing and CO2 injection are both high enough. This follows from simple math, mentioned in several other posts, and will not elaborate again here. Irrespective of the injection method (diffuser, reactor, CO2 Spray Bar), a good CO2 stability can only be achieved with good surface agitation (gas exchange), and avoiding any changes in the surface agitation. Changes of the flow pattern and surface agitation (e.g. adjust spray bar or lily pipe) have a significant impact on the tank CO2 ppm and stability.
• For tanks with good surface agitation, a requirement for good stability, both injection and outgassing will usually be much higher than the plant CO2 uptake. Changes in plant mass, growth or pruning, do change plant CO2 uptake, but this is likely to be minor as compared to total CO2 injection and outgassing. With tank maintenance and heavy pruning, the change in waterflow may outweigh the impact of removing plant mass. Unless pH is precisely monitored with a probe, adjusting CO2 injection for plant mass may very well be counterproductive for CO2 stability.

1. ‘Overflow Mode’

As the meniscus of CO2 will align itself with the overflow, the CO2-water absorption area will be constant. With the CO2 Spray Bar mounted in front, and in the flow of the water spray bar the flow at the absorption interface is stabilised as well unless the filter clogs up.

The quality and stability of the CO2 regulator is no longer important, as long as it injects enough. I usually set it so that I see a bubble of CO2 escape from the overflow every few minutes, and then don’t worry any more. Monitoring flow rate and using a bubble counter is no longer needed, just watch the overflow in action and if it ‘runs dry’ increase the injection a bit.

I use different overflow end pieces, with the hole drilled in different positions to adjust the CO2 reservoir capacity to my liking. This works better than the rotation that I used to do, as it is important to rule out unwanted changes in the position of the overflow.

For levelling the CO2 Spray Bar horizontally, so that geometry is reproducible, I use the tank water surface as a reference, or alternatively a few bubbles of air or CO2 in the nearly empty spray bar.

The main factor that will drive both short term and long term CO2 stability are the surface agitation / gas exchange.


2. ‘Regulator Mode’

We set the overflow so that under normal operation the CO2 meniscus will never reach it, and no CO2 will escape from the overflow. The system will then stabilise when CO2 absorption = CO2 injection from the regulator, and we have a very similar function as with a traditional inline reactor.

Now, of course, we need a good quality CO2 regulator that is both short term stable, and has no long term (day-to-day and week-to-week) drift. we need to use a bubble counter to regularly monitor & finetune the injection rate

While the CO2 Spray Bar functions mostly as in inline reactor, it eliminates most of the traditional reactor’s challenges. No noise. No flow reduction for filter. No safety concern when a cylinder blow out or regulator malfunction causes too much CO2 injection. No CO2 mist in tank.

The main factor that will drive both short term and long term CO2 stability are surface agitation / gas exchange, as well as instabilities and drift from the CO2 regulator.


3. ‘CO2/pH controller mode’

As with Regulator Mode, but instead using a CO2/pH controller to stabilise pH within a given bandwidth.

While the CO2 Spray Bar functions similar to an inline reactor, as per above, it eliminates most of the traditional reactor’s challenges. No noise. No flow reduction for filter. No CO2 mist in tank.

With a proper setting of the overflow, it can be used to fully maintain the function of a correctly working pH controller, while mitigating risks sometimes associated with the CO2/pH controller. When the controller injects more than a safe level of CO2 (malfunction, probe or KH change) the CO2 overflow will act as a safety valve and limit the maximum CO2 that the Spray Bar can inject.

The main factors that will drive CO2 stability are the KH stability, calibration of pH probe, and upper/lower limits pH setting.

 

[Hufsa]

Hi @22802 , Im posting my questions here in this thread because I think it makes the most sense, but let me know if you want me to start a separate thread 😊
My current reactor (Yidao) is struggling a lot to keep up with my injection rate/surface agitation/flow combo, and as we have already discussed a bit earlier I want to try the CO2 spray bar on my system to see if it is a good fit for me.

Design rules / estimation
For my tank (100 * 45 * 60 cm) I use a 1 inch, 90 cm long CO2 spray bar This is 216 cm2 surface area. The ratio between tank surface area (4500 cm2) and CO2 spray bar (216) is 20.8 :1. For other tank dimensions, this ratio is a good approximation how to find the optimal dimensions of the spray bar.

Im hoping you may be willing to provide a little bit of "hand holding"? Because of my chronic illness my working memory is affected and particularly these days doing mathematical calculations is especially difficult.
If youre willing could you help me make the determination for what size diameter and length of bar I need on my tank?
My tank is 100cm long and 50cm wide. I have PVC pipes in a variety of diameters already that I can use for the CO2 spray bar itself.
I would prefer if the CO2 spray bar was about 80cm long or a little less, longer than this and it might start to conflict with the pipes on the left and right side of the tank.
To refresh I have one water spray bar along the top of the tank's back wall, and (rather unusually) one bottom spray bar on the substrate that sends water up along the back glass pane.
I am thinking of mounting the CO2 spray bar directly below the top water spray bar, I dont think the current from the bottom water spray bar is strong enough to cause issues with the CO2 meniscus, and I wonder if it might actually be a benefit as the water movement up the back wall is much more stable with this setup than on a tank with no bottom spray bar and increasingly thick masses of plants at the back. Let me know if you require pictures of this setup.

I was thinking to aim the calculations on the CO2 spray bar a little high (maybe 1.2-1.4 drop?) and then adjusting down to 1.0 drop using one of your holes in the end cap. Do you still use 5mm?
Just to avoid the issue of making a CO2 spray bar that is under capacity, and needing to make a second bar.
Unfortunately PVC pipes are more expensive to acquire here, I wish we had your material costs.
I will try out with a grey PVC pipe first that is spray painted black, and then if I am happy with how it works on my setup I can buy an (expensive) black PVC bar and recreate the CO2 spray bar with the same measurements.

 

[Hufsa]

I just realised I could treat the surface area of half a spray bar as a flat plane, so it would just be a matter of taking the inner diameter x length of the bar
I had somehow imagined the calculation to involve pi, calculating the volume of half a cylinder, quantum mathematics, one trampoline and two sacrificial goats and my brain just went "nope"

 

[22802]

Hi @22802 , Im posting my questions here in this thread because I think it makes the most sense, but let me know if you want me to start a separate thread 😊
My current reactor (Yidao) is struggling a lot to keep up with my injection rate/surface agitation/flow combo, and as we have already discussed a bit earlier I want to try the CO2 spray bar on my system to see if it is a good fit for me.



Im hoping you may be willing to provide a little bit of "hand holding"? Because of my chronic illness my working memory is affected and particularly these days doing mathematical calculations is especially difficult.
If youre willing could you help me make the determination for what size diameter and length of bar I need on my tank?
My tank is 100cm long and 50cm wide. I have PVC pipes in a variety of diameters already that I can use for the CO2 spray bar itself.
I would prefer if the CO2 spray bar was about 80cm long or a little less, longer than this and it might start to conflict with the pipes on the left and right side of the tank.
To refresh I have one water spray bar along the top of the tank's back wall, and (rather unusually) one bottom spray bar on the substrate that sends water up along the back glass pane.
I am thinking of mounting the CO2 spray bar directly below the top water spray bar, I dont think the current from the bottom water spray bar is strong enough to cause issues with the CO2 meniscus, and I wonder if it might actually be a benefit as the water movement up the back wall is much more stable with this setup than on a tank with no bottom spray bar and increasingly thick masses of plants at the back. Let me know if you require pictures of this setup.

I was thinking to aim the calculations on the CO2 spray bar a little high (maybe 1.2-1.4 drop?) and then adjusting down to 1.0 drop using one of your holes in the end cap. Do you still use 5mm?
Just to avoid the issue of making a CO2 spray bar that is under capacity, and needing to make a second bar.
Unfortunately PVC pipes are more expensive to acquire here, I wish we had your material costs.
I will try out with a grey PVC pipe first that is spray painted black, and then if I am happy with how it works on my setup I can buy an (expensive) black PVC bar and recreate the CO2 spray bar with the same measurements.

Great to see you make this move @Hufsa , and happy to help with as much info and help as you may need 🙂

My tank is 100cm long and 50cm wide.

Mine is nearly same size, 100 * 45 cm, so that makes it easy to copy my setup to your tank. My CO2 Spray Bar is 80 cm long, and made of a pipe with 1 inch diameter (2*radius). The tank's CO2 need obviously depends on certain variables, mostly surface agitation, but the important reference point is that my CO2 Spray Bar gives about 1.5 pH drop when at full capacity (that is, the meniscus is 1 inch, 2.4 cm wide and 80 cm long ).

My recommendation therefore would be to use a 1 inch diameter pipe, so that your bar is not the limiting factor and you don't need to cut a second one. If you like to lower the capacity later you can test different end pieces with holes drilled in different positions to play with the meniscus.

I am thinking of mounting the CO2 spray bar directly below the top water spray bar, I dont think the current from the bottom water spray bar is strong enough to cause issues with the CO2 meniscus, and I wonder if it might actually be a benefit as the water movement up the back wall is much more stable with this setup than on a tank with no bottom spray bar and increasingly thick masses of plants at the back.

I believe this set up would work really well. I would not worry about the flow of the bottom water spray bar disturbing the CO2 meniscus, you would need a huge flow to blow CO2 out from the pipe. Your setup also makes the mounting of the CO2 Spray Bar easier than in my setup, as I needed to find a way to attach my CO2 Spray bar to my water spray bar.

From your journal I know that you have some issues with your tank recently, and I imagine you don't want to add additional challenges playing with your CO2 ppm. I believe the smart way would be to not touch your CO2 regulator and bubble counter, and to just bring your CO2 tubing from your Yidao reactor to your newly installed CO2 Spray Bar. In that way your are sure that at least initially you are at same CO2 injection rate into the water, and normally the CO2 Spray Bar would work under its maximum capacity (it is now the regulator that sets the CO2 injection, not the CO2 overflow). When this works fine, you may start to slowly adjust CO2, either by adjusting your regulator or by using different end pieces with different hole positions (yes, I use 5 mm) to set the meniscus.

Im hoping you may be willing to provide a little bit of "hand holding"?

More than happy, do let me know if you have any questions 🙂

 

[Hufsa]

(that is, the meniscus is 1 inch, 2.4 cm wide and 80 cm long )

1 inch pipe would be 25,4mm diameter, I figure I can use a metric 25mm pipe then?
So I gather your calculations are based on outer diameter? It doesnt matter really, I just wanted to use the same to keep things the most similar. Things are gonna be off by some milimeters here and there anyways and the final adjustment done by the 5mm hole in one end piece.

My recommendation therefore would be to use a 1 inch diameter pipe, so that your bar is not the limiting factor and you don't need to cut a second one.

Great I will check "my stash" tomorrow to see if I have end pieces for 25mm pipe, if not it makes a good(/dangerous) excuse to go to the pet store again 😅

If you like to lower the capacity later you can test different end pieces with holes drilled in different positions to play with the meniscus.

Fairly sure I will need to do this, but having it adjustable like that is just a bonus not a drawback of the bar.

I believe this set up would work really well.

I hope so!

From your journal I know that you have some issues with your tank recently, and I imagine you don't want to add additional challenges playing with your CO2 ppm.

Honestly right now my CO2 injection is relatively high but not stable, Ive been measuring it over the past days using my new ph pen and it looks like the reactor is having trouble stabilizing itself after I changed the skimmer to run only at night. So there is already unstable levels during the photoperiod and a ton of BBA. Making the switch makes me nervous of course, but its possible that this will bring stability to the tank quicker than other options would have.

I believe the smart way would be to not touch your CO2 regulator and bubble counter, and to just bring your CO2 tubing from your Yidao reactor to your newly installed CO2 Spray Bar. In that way your are sure that at least initially you are at same CO2 injection rate into the water, and normally the CO2 Spray Bar would work under its maximum capacity (it is now the regulator that sets the CO2 injection, not the CO2 overflow). When this works fine, you may start to slowly adjust CO2, either by adjusting your regulator or by using different end pieces with different hole positions (yes, I use 5 mm) to set the meniscus.

I can try, but the injection rate right now is ridiculous because ive been trying to get it dialed in again and failing. So if theres a ton of gas escaping from the bar then I will probably tune it down relatively soon.

More than happy, do let me know if you have any questions 🙂

Will do 😊

 

[22802]

1 inch pipe would be 25,4mm diameter, I figure I can use a metric 25mm pipe then?
So I gather your calculations are based on outer diameter? It doesnt matter really, I just wanted to use the same to keep things the most similar. Things are gonna be off by some milimeters here and there anyways and the final adjustment done by the 5mm hole in one end piece.

Yes, 25 mm should be fine and I would expect that to give you around 1.5 pH drop maximum. If you, at least initially, continue to use your regulator in its current settings then the hole in the end piece will not really make a difference.
(I currently use my pH/CO2 controller again, and then the overflow is only acting as a safety valve if anything goes wrong.)

Fairly sure I will need to do this, but having it adjustable like that is just a bonus not a drawback of the bar.

It is so easy to drill a hole in an end piece. I now have a couple of end pieces that I can interchange. I prefer that over rotating my end piece, as I described earlier in this thread, as I need to worry less about reproducibility.

the injection rate right now is ridiculous because ive been trying to get it dialed in again and failing. So if theres a ton of gas escaping from the bar then I will probably tune it down relatively soon.

The spray bar gives always 100% dissolved gas (unless bubbles escape from overflow), so there is no risk for any mist to appear in the tank. What you may do is to start with a 5 mm hole drilled in the centre, as you see in my current setup below, this will give a meniscus that is nearly at maximum and I would estimate a pH frop around 1.5. Obviously plants react better to increased CO2 ppm than to decreased CO2, so if your fish are OK this could be a good way to go initially.

EDIT: I realise that @Hufsa tank surface is 10% more than mine, which will give higher outgassing. When I mentioned pH drop estimation of 1.5, this was based on my own tank dimensions and should be corrected for the increased outgassing in @Hufsa tank. On the other hand, in my tank the pH drop is actually slightly above 1.5, closer to 1.6 (which means 25% more CO2 ppm than 1.5 equivalent). In summary, if I remember correctly @Hufsa targeting usually 1.0-1.2, a one inch spray bar is most likely enough to do the job. With progressively more users with CO2 Spray Bar, we will get better statistics as to the best dimensions for any tank size.

 

[DuyHung]

Does it work for 24/7 Co2? I hate the reactor noise so maybe try this one. Thanks for idea 🥰

 

[sparkyweasel]

o involve pi, calculating the volume of half a cylinder, quantum mathematics, one trampoline and two sacrificial goats

No need, it can be performed with a simple incantation, three small bits of wood and 4cc of mouse blood. 🙂

 

[22802]

Does it work for 24/7

No problem, you can have your (spray) bar open 24/7 🍻🎊🎶

(So no problem for CO2 Spray Bar or injection, but most hobbyist use CO2 only before/in photoperiod, say 12 hours -reduce CO2 consumption and more comfort for lifestock during night when O2 is low)

 

[DuyHung]

Actually, my electric coil has broken 🤣 so I open 24/7 co2. Since I have tried this method, my PH drop 1.5 I think its ok but my dropcheck seem not chage so much. Its still green but I aim to yellow because I want OP co2. Btw I have a ques. Where should be the Co2 spraybar compair to water surface and water spraybar ? Rightnow, I place water spraybar directly equal surface and the co2 is below a little.
Thanks for help. I well note with this method I have no more noise compair to reactor 😃

 

[22802]

Where should be the Co2 spraybar compair to water surface and water spraybar ?

I set it up as you can see earlier in the thread, my CO2 Spray Bar is at the water surface and the water spray bar just below:


@Hufsa has the CO2 Spray Bar just below the water spray bar, but she has a second water spray bar that creates a flow from bottom to top at the back of the tank and is making sure the CO2 Spray Bar gets enough flow:


It is important that the water spray bar always gives the same surface agitation, so that CO2 outgassing is constant. Furthermore, there should be a good flow of water around the CO2 Spray Bar. For the rest, there are many ways to make it work, including placing the CO2 Spray Bar at the front of the tank as I did initially.

 

[anewbie]

I'm having problems following this - and i might have missed something critical. I saw this topic as I am working on a reactor for a 550 gallon aquarium. What my reactor and store purchase reactors have in common is that the co2 is injected in the top but the water flows out of the bottom so the co2 has to dissolve before it can flow out the bottom - the error is if you put in enough co2 to allow the bubbles to reach the bottom - the reactor i am making is 2 feet tall. Now when i look at the spray bar i'm missing how you force 100% dissolving before the co2 can escape out the tube - i.e, what prevents some of it escaping in gas form.
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Now this part is not really related - but i had two options i could connect the reactor to the return pump directly - i am worried that if i only use 1 return pump on the output the co2 was not be evenly distributed - after all the aquarium is 10 feet long; conversely (and this is what i am trying) i could send the co2 into the sump tub where the returns are located so all 4 returns can picked up the co2 rich water (the concern with that approach is some of the co2 might gas off before being sent into the aquarium - but the co2 is more evenly distributed since all the returns are returning co2 rich water. With a tank this large i would like very high efficiency since well it can end up using quite a bit of co2. The reactor in question is being made out of a pentair water filter housing - and the total cost (with the bulk being the housing) is around $80 - pentair housing around $50 and then various brass fittings for the rest of it.

 

[22802]

I'm having problems following this - and i might have missed something critical. ... Now when i look at the spray bar i'm missing how you force 100% dissolving before the co2 can escape out the tube - i.e, what prevents some of it escaping in gas form.

If I correctly understand your question, I hope the following picture explains it. We have two spray bars, the first (left in picture) pushing return water from the canister/sump (or perhaps a simple circulation pump), and then the CO2 Spray Bar (in red below) that is filled with CO2 (there is no water pumped into the CO2 Spray Bar). The CO2 Spray Bar does not generate any bubbles, as it is just a 'stationary' CO2 gas pocket above the water flow from the water spray bar.

I am working on a reactor for a 550 gallon aquarium

It is possible, but not easy and not cheap to make a conventional vertical reactor for this size of tank. You may want to check out Horizontal CO2 Reactor , that works on the same principles as the CO2 Spray Bar, but then as an inline version. (In the thread I also estimate the 'design rules', ie how to calculate the reactor dimensions for your tank size.)

Now this part is not really related - but i had two options i could connect the reactor to the return pump directly - i am worried that if i only use 1 return pump on the output the co2 was not be evenly distributed - after all the aquarium is 10 feet long; conversely (and this is what i am trying) i could send the co2 into the sump tub where the returns are located so all 4 returns can picked up the co2 rich water (the concern with that approach is some of the co2 might gas off before being sent into the aquarium - but the co2 is more evenly distributed since all the returns are returning co2 rich water. With a tank this large i would like very high efficiency since well it can end up using quite a bit of co2. The reactor in question is being made out of a pentair water filter housing - and the total cost (with the bulk being the housing) is around $80 - pentair housing around $50 and then various brass fittings for the rest of it.

Your point about CO2 distribution is very valid, but as you are aware a sump will cause additional CO2 losses. I have seen postings where the sump was covered with a lid to reduce CO2 losses, but one may argue that this would also reduce the so important O2 exchange in the sump.