Injected CO2 End of Tank dump

1910 Views 7 Replies 6 Participants Last post by jeffkrol, Oct 1, 2016

Roarke

Discussion Starter · Oct 1, 2016

Sorry, I know this has come up before. I tried to search but it literally didn't work, I got an Internal server error.

I spent a good amount of money from a reputable member of these forums on a co2 system. I was under the impression that a quality dual stage regulator would prevent end of tank dumps. Is this true? I came home to fish gasping at the top. The first stage had dropped from just above 1000psi to about 400psi. The second stage is still at ~38 psi, where I have it set to. I've never seen the fish gasp so I'm pretty sure more co2 was released than normal.

Do you guys agree there was an end of tank dump? If so, what can I do to prevent it?

Thanks!

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Immortal1

· #2 · Oct 1, 2016

From what I have read above, I would guess you have your bubbles per second set very close to the ragged edge of what your fish will tolerate. I have run into this a few times where the fish start complaining (gulping air) when I have the bubble count too high (again, we are talking 3.5 bps vs 3 bps). As for the end of tank dump, a good 2 stage (assuming you have one) will prevent end of tank dump). You should be able to run your tank down to 0 psi without dumping excess cO2 into the tank. Myself and others have run their 2 stage regulators down to less than 100psi without problems.
As to how to prevent it, maybe lower your bps flow slightly.

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Nlewis

· #3 · Oct 1, 2016

What you are referring to as first stage it the tank pressure. It dropping 600psi tells me that you have a leak somewhere.

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jeffkrol

· #4 · Oct 1, 2016

Roarke said:
Do you guys agree there was an end of tank dump? If so, what can I do to prevent it?

Thanks!

No
But you might have something wrong w/ your valve or a flaky check valve can cause problems..

Single-Stage Regulator
Single-stage regulators are an excellent choice for relatively small reductions in pressure. For example, the air compressors used in most factories generate maximum pressures in the 100 to 150 psi range. This pressure is piped through the factory but is often reduced with a single-stage regulator to lower pressures (10 psi, 50 psi, 80 psi etc.) to operate automated machinery, test stands, machine tools, leak test equipment, linear actuators, and other devices. Single stage pressure regulators typically do not perform well with large swings in inlet pressure and/or flow rates.
Two-Stage (Dual Stage) Regulator
A two-stage pressure regulator is ideal for applications with large variations in the flow rate, significant fluctuations in the inlet pressure, or decreasing inlet pressure such as occurs with gas supplied from a small storage tank or gas cylinder.
With most single-stage regulator regulators, except those that use a pressure compensated design, a large drop in inlet pressure will cause a slight increase in outlet pressure. This happens because the forces acting on the valve change, due to the large drop in pressure, from when the outlet pressure was initially set. In a two-stage design the second stage will not be subjected to these large changes in inlet pressure, only the slight change from the outlet of the first stage. This arrangement results in a stable outlet pressure from the second stage despite the significant changes in pressure supplied to the first stage.

..

Bump:

Nlewis said:
What you are referring to as first stage it the tank pressure. It dropping 600psi tells me that you have a leak somewhere.

At the end of the tank pressure will drop "relatively" fast..
Though "if" the tank is large (@1000psi points to a larger tank or overfilled..#5 generally don't exceed 600-800psi at "room temp"

Your pressure gauge should never read more than 1000 psi. If it does but your room temp is below 80, suspect that the gauge needs recalibrating.

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Seattle_Aquarist

· #5 · Oct 1, 2016

Roarke said:
Sorry, I know this has come up before. I tried to search but it literally didn't work, I got an Internal server error.

I spent a good amount of money from a reputable member of these forums on a co2 system. I was under the impression that a quality dual stage regulator would prevent end of tank dumps. Is this true? I came home to fish gasping at the top. The first stage had dropped from just above 1000psi to about 400psi. The second stage is still at ~38 psi, where I have it set to. I've never seen the fish gasp so I'm pretty sure more co2 was released than normal.

Do you guys agree there was an end of tank dump? If so, what can I do to prevent it?

Thanks!

Hi Roarke,

This is how I see it. If your first stage (tank pressure) dropped from above 1000 to about 400 psi I am guessing the ambient temperature is high where the tank is kept; a full CO2 tank typically runs +/- 800psi. The reason the pressure dropped from 1000 to 400 psi is all the liquid CO2 in the tank has been depleted and all that is left is CO2 gas which is being used up. If the second stage (line pressure) is still at 38psi the regulator is doing what it should and I doubt you experienced an EOD event.....especially with a dual stage regulator.

You didn't indicate what ppm level you target the CO2 for that tank. If you are running above 30ppm CO2, have a high ambient temperature and/or a warm light fixture, and/or reduced water circulation possibly due to filter media becoming heavily soiled then those conditions could have triggered the fish distress. It could have been excessive CO2 or it could have been a lack of O2 that caused the fish distress; if a tank is overcrowded, cloudy, or doesn't receive sufficient water changes on a regular basis.

I would look elsewhere for the problem that triggered the fish distress, it does not seem likely it was a regulator issue of EOD.

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Joshism

· #6 · Oct 1, 2016

Tell us what else have you done recently? Every time I change my water and use Kordon NovAqua Plus and Amquel, all my fish are gasping at the surface. Do a soap leak test. I'm doubting that it's EOTD. Show us your regulator.

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Roarke

Discussion Starter · #7 · Oct 1, 2016

jeffkrol said:
At the end of the tank pressure will drop "relatively" fast..
Though "if" the tank is large (@1000psi points to a larger tank or overfilled..#5 generally don't exceed 600-800psi at "room temp"

I'll look into calibrating it. I've had it filled twice and it sat around the same PSI when full, over 1000.

Nlewis said:
What you are referring to as first stage it the tank pressure. It dropping 600psi tells me that you have a leak somewhere.

The tank has lasted over 7 months. I think it's a little strange for a leak to suddenly happen.

Seattle_Aquarist said:
Hi Roarke,

This is how I see it. If your first stage (tank pressure) dropped from above 1000 to about 400 psi I am guessing the ambient temperature is high where the tank is kept; a full CO2 tank typically runs +/- 800psi. The reason the pressure dropped from 1000 to 400 psi is all the liquid CO2 in the tank has been depleted and all that is left is CO2 gas which is being used up. If the second stage (line pressure) is still at 38psi the regulator is doing what it should and I doubt you experienced an EOD event.....especially with a dual stage regulator.

You didn't indicate what ppm level you target the CO2 for that tank. If you are running above 30ppm CO2, have a high ambient temperature and/or a warm light fixture, and/or reduced water circulation possibly due to filter media becoming heavily soiled then those conditions could have triggered the fish distress. It could have been excessive CO2 or it could have been a lack of O2 that caused the fish distress; if a tank is overcrowded, cloudy, or doesn't receive sufficient water changes on a regular basis.

I would look elsewhere for the problem that triggered the fish distress, it does not seem likely it was a regulator issue of EOD.

I think you may be right here. I temporarily removed a powerhead which significantly reduced water flow, I hadn't though about the two being related (I mean it did happen the same day as the co2 changing phases). It was probably causing a more surface agitation/gas exchange. I was pushing the limits a bit on how much CO2 i was injecting, based on advice to deal with some algae.

Follow up question, do you think I should lower the amount of co2 I'm using even if I add the powerhead back in?

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jeffkrol

· #8 · Oct 1, 2016

Roarke said:
1
Follow up question, do you think I should lower the amount of co2 I'm using even if I add the powerhead back in?

I "believe" in the less is more philosophy myself.
There is no need for, say 30ppm CO2.
Injecting much smaller quantities is as beneficial and less risky..

Whole thread w/ some good discussion:
http://www.plantedtank.net/forums/1...078889-effect-co2-plant-growth-low-light.html

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