# 3.5L of co2 with 4bps can last how long



## heavenkid (31 Jul 2018)

Hii everyone, is it normal for my case. A 3.5litre co2 tank with 4 bps run for 9hrs daily for a 48 gallon tank last about a month.

I tried using soapy water to test for leak but cant find any

I using a intense co2 solenoid regulator with a intense atomizer.


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## ian_m (31 Jul 2018)

This cant be answered as not enough info...

How big are your bubbles, so we can know the volume used ????

CO2 is sold by weight, not volume.

Is your drop checker green ?

Anyway, I get about 100 days from 2Kg CO2 on 180litre (40 gallon) tank on for 8 hours with green/yellow drop checker. My bps is 1-2 type range, don't really know as never measured, bps just indicates gas is flowing in your setup.

So one month, even for 2Kg is a tad low, but if you have poor CO2 injection, mine is inline diffuser, that amount is probably ok.


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## Zeus. (31 Jul 2018)

If that was 3.5Kg you was using with a big pH drop it would sound about right. Like Ian says BPS is just an indication of the rate- bit like comparing speed and velocity!
I  use 6.5KG a month on my 500l which also has CO2 reactors, so it eats the stuff, even though I have a six hour photoperiod.
However I do have a big pH drop well over 1.0 and DC is nearly clear (caution having such a big pH drop!)
My BPS is crazy high a can not count it and adjust the CO2 working pressure via reg to fine tune the injection rate.
The higher the [CO2] in the tank the faster thre CO2 is lost from the tank making it less efficient IMO/IME.
The 1.0pH drop in my tank is fast, but that extra 0.3 - 0.5 pH drop takes much longer.
Bigger tanks need more turnover to combat there size so they use more CO2/Litre compounded by your hardscaping, depth of tank and carpet.


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## alto (31 Jul 2018)

CO2 is typically sold in Singapore by volume not weight 

Air Products provides this conversion table 
- assuming 300psig, 3.5 l CO2 would be approximate 3.5kg CO2 ... which seems a rather high usage rate 

Check for CO2 leaks under solenoid ON & solenoid OFF conditions
Also soapy water is not the best detection solution - a commercial solution such as Snoop can detect leaks easily missed using soapy water


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## ian_m (31 Jul 2018)

alto said:


> Air Products provides this conversion table
> - assuming 300psig, 3.5 l CO2 would be approximate 3.5kg CO2


That table is of no use, 300psi is of no interest. CO2 in cylinders is supplied as a liquid and to get liquid CO2 at room temperature pressure will be 55bar about 800psi. Liquid CO2 is sold by weight, they weigh the empty cylinder and add the required weight. The cylinders are only ever filled to a maximum of about 2/3 of their volume, so a 5 litres cylinder is filled to 3.75Kg (3.75l) to allow room for expansion if cylinder gets considerably hotter than room temperature.

You need to weigh your cylinder + regulator before CO2 and after to determine how much CO2 you are using in one lighting period.

I get through roughly 20gr a day in 180litre in 8 hours which is 20/180/8 -> 0.014 grams per litre per hour.

Assuming you mean 3.5Kg CO2 cylinder, for 9 hours in 220 litres and using my CO2 consumption -> 0.014 x 9 x 220 -> 28g per day, so 3.5Kg should last 3500/28 -> 125 days.

You are using 3500/30 -> 115 gr per day.

So you either have a leak somewhere or your CO2 injection method is very questionable, but I would expect to get more than 30 days from 3.5Kg CO2.

Looking what an intense atomiser is, reveals this is the issue. You will not be able to get any decent level of CO2 in a large tank using just one of these atomisers, most CO2 will simply be lost, especially at high injection rates. For large tanks, you really must use in line injection or CO2 reactors so as to not waste most of your CO2.


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## HiNtZ (31 Jul 2018)

Depends on the size of the bubbles. On a 4mm exit hole at 4bps a 5kg will last 4-6 months tops.


If you're using a smaller bubble counter like this style







 with the little plastic hole as an opening at the bottom (about 1mm), then 4bps on a 5kg will last 8 months. Maybe a little more.

These are my experiences, obviously there are variables that would change in different scenarios but it'll give you an idea of how often you will have to consider getting a refill which isn't actually often. I just stock up on fire extinguishers, enough for at least 4 years.

You will have a week or two of dropping pressure toward the end of the bottle. It's always a good idea to change it out as soon as you start to see the high pressure side needle drop down past 500psi.

There's definitely something wrong here though. I would swap the reg out for a month and eliminate that. Could be a perished diaphragm in the regulator seeping or something.


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## Zeus. (31 Jul 2018)

Did the rough maths for mine
6.5Kg , 30day, 6hrs, 500litres
So 0.072g/l/HR which is high OFC, but until I improve the my tank turnover I'm leaving it as it is, plants/carpet doing well livestock happy algea under control.
Did read you should treat CO2 as if its free- only then will you use it to it's full potenial

Wouldn't mind having to do less refills all the same


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## alto (31 Jul 2018)




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## Franks (31 Jul 2018)

I’ll throw my hat in the ring and say I think you are using too much gas for that tank. A leak, poor distribution etc. 

I use 2.5 Kg on my 155ltr 2 ft deep tank using inline diffuser and that lasts around 2.5 months. Bubble rate is uncountable on the JBL inbuilt counter and the counter supplied with my co2art dual stage reg. It was also uncountable on the single stage inbuilt reg. ~8 or 9 bps! Lime green DC and a pH drop of 1. 7 hour light period with gas on 8 hours per day 


Sent from my iPhone using Tapatalk


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## Zeus. (31 Jul 2018)

Franks said:


> I use 2.5 Kg on my 155ltr 2 ft deep tank using inline diffuser and that lasts around 2.5 months. Bubble rate is uncountable on the JBL inbuilt counter and the counter supplied with my co2art dual stage reg. It was also uncountable on the single stage inbuilt reg. ~8 or 9 bps! Lime green DC and a pH drop of 1. 7 hour light period with gas on 8 hours per day



So

2.5Kg/75days/8hrs/155litres = 0.027g/l/hr approx


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## Zeus. (31 Jul 2018)

ceg4048 said:


> I had my tank in the conservatory I was consuming a 22Kg cylinder every 5-6 weeks in my 700L tank.



I will assume a 8hr photo period

22Kg/42days/8hr/700litres = 0.094g/l/hr


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