New starter (CO2 questions)

Discussion in 'Carbon Dioxide (CO2)' started by stevet, 25 Oct 2007.

  1. stevet

    stevet Member

    Messages:
    80
    Location:
    London
    I have recently planted out a 400 litre tank with some relatively undemanding plants - swords, hygrophila, vallis etc etc. I wanted to have this tank co2 injected and opted (somewhat inadvisably) for the carbo plus system. After much discussion on the american planted tank forum and research on the net it turns out this product is extremely suspect in what it claims to do, and is in no way adequate for a 400litre tank anyway. I decided to trade this in for a pressurised system. Again further research has revealed that the 600gm bottle that i ordered with my D-D co2 kit will not last a month in my tank.

    I also run an eheim wet/dry filter wich will effectively outgas a lot of my co2! Therefore a 600gm bottle a)isnt big enough for the tank size anyway and b) wont last long at the ridiculous bps rate i will need to keep my drop checker showing green in a wet/dry filtered tank.

    My question(s) is this then:

    Is there no hope for me achieving adequate co2 levels without resorting to large scale FE usage and risking life and limb in the process?!? Or harbouring a potentially lethal missile in my house? I cant be bothered with the hassle of changing a 600gm bottle every month - not mention the cost?

    Could i change to just using seachems flourish excel as a source of carbon for the plants? At 2.7 wpg i am practically running a low tech lighting regime anyway? I use a eco-complete substrate. So with decent fertilisation routine and moderate lighting i would have two of the three boxes ticked? Anyone know if flourish excel is decent alternative to injected co2?
     
  2. fishgeek

    fishgeek Member

    Messages:
    117
    Location:
    west sussex
    if the eheim is a sealed filter unit, where exactly would the CO2 be lost too?

    just a theoretical question, yes it may leave the water in as gas, accumulate in that gas till saturation pressure where equal and then the rest would stay in the water?

    someone will know more about that than my addled logic suggest, i think too many reponse's on internet come from reading it somewhere else and not actually really understanding

    i use a jbl system, i can for my system purchase a 2 kg bottle, expensive intial outlay, refill's are more affordable, i think other will be able to advise whether that is possible with your system or whether prehaps the threads are universal

    andrew
     
  3. George Farmer

    George Farmer Founder Staff Member

    Messages:
    7,089
    Location:
    Cambridgeshire
    Welcome to UKAPS, Steve!

    I'm not sure who told you 2.7wpg is low-tech. It's actually high light in that tank size and you'll be able to grow anything...

    I'd recommend pressurized CO2 for sure. Excel alone won't provide sufficient carbon to feed the plants' need with all that light.

    Either that or half your light and run Excel. This will be expensive too. Excel isn't cheap either.

    I don't see how an FE is really more dangerous than a disposable cylinder.

    The contents pressure are the same - 60 bar give or take. Abuse either and the consequences will be similar...

    As long as you take care when fitting and removing the reg, the risks are negligible.

    If you're really worried about FE then 2Kg aquarium-use cylinders are available.

    As for wet/dry filters, have you considered changing to a regular canister? In a heavily planted tank, the plants perform the vast majority of the bio-filtration, with the filter being more useful for circulation.

    I've also heard that it's possible to seal the wet/dry part so CO2 isn't driven off. Tom Barr does this.

    Anyway, I hope that helps a little.
     
  4. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    Hi Steve,
    I agree with George and Andrew.
    AFAIK, the Ehiem wet and dry unit is sealed and therefore the gas in the filter will reach and equilibrium with the dissolved gas in the water and then, once they are the same the CO2 coming out of solution will be matched by the same amount of CO2 going back into solution from the gas.

    A fire extiguisher is just a cylinder like other CO2 canisters so I can't see how it would be any more dangerous. It's just a CO2 cylinder with a slightly different outlet. I don't know if you've seen it but there's a great write up by Sam in the tutorials section, http://ukaps.org/forum/viewtopic.php?t=266 although the first lines may not do anything to allay your concerns...
     
  5. beeky

    beeky Member

    Messages:
    879
    Location:
    Chippenham, Wiltshire
    For FishGeeks benefit, a wet/dry filter (as I understand it) allows a larger quanity of bacteria to form on the media as the oxygen content is higher. It achieves this by alternately flooding and draining the water in the filter. I would imagine this would be akin to high surface agitation with a normal filter outlet, thus driving off the CO2.
     
  6. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    The Ehiem one is a sealed bit that sits on the side of the ordinary external filter Beeky. As it's sealed it won't have quite the same effect as a normal open wet and dry filter, well it shouldn't anyway!
     
  7. stevet

    stevet Member

    Messages:
    80
    Location:
    London
    ok firstly thanks for the replies - on the wet/dry - this is not a sealed unit as people may think - there is an air inlet hose that allows air into the chamber unit to be mixed with water in the media chamber. Therefore it is not sealed in the same way an ordinary cannister is. They are excellent filters and i believe do work better than ordinary cannisters at getting o2 to the filter bacteria but they are a pig for outgassing co2! Some people seem to think a reactor is the way to go with the wet/dry as this will enrich the water with co2 better than anything else? Better than diffusers....?

    OR my current carbo plus unit is utter blahblahblahblahblahblah and is in no way providing anywhere near enough co2 to my 400 litre tank to make any difference? When i swap to pressurised i will notice my co2 content leap up!?! Many people believe carbo plus produces more hydrogen than co2 anyway and that the cathode anode relationship is misadvertised by Zac and is in fact incorrect chemistry? George - didnt you recommend them in PFK? Whats your view?

    I may swap my wet/dry for my smaller but less co2 unfriendly professionel2 unit. It will save on masses of co2 in the long run i believe. I will then have to carefully monitor o2 levels in the water as i will have no wet/dry enriching the water with co2 for me? I just feel that i will be solving the co2 problem only to change it for an o2 one (given that my plants dont seem to be providing a lot of o2 into the water?) I see no pearling currently.

    As for FEs - i was hoping to avoid using them but i guess they are a necessary item. You are right - they would logically be no less dangerous than using and 2kg specialist aquarium one. Ill use the 600gm with the wet/dry and then if i lose too much co2 ill swap to the professionel2 and see how far this gets me.

    Thanks for comments on the lighting - however if i use rex griggs lux calculator i come out at 18 lux per square inch - which is just above low lighting levels. He disputes the wpg rules accuracy and validity in large tanks like mine? I have 3x54w luminaire and 2x55W interpet compacts - all T5s. This gives me 272 watts (?) /by 100 gallons (US) = 2.7wpg. Try using the grigg lux calculator based on the lumens for each of these bulbs which is 3600 lumens average - i may have done the maths wrong? Anyway it seems the lumens based calculation comes out a lot lower than the wpg rule?
     
  8. George Farmer

    George Farmer Founder Staff Member

    Messages:
    7,089
    Location:
    Cambridgeshire
    Hi Steve

    I dispute lux per sq. inch too...

    Lux (lumens per sq. metre) is a measurement of our eyes' sensitivity to light, not physical light. Green causes the highest light perception, and green is the least useful light for plant growth.

    It's a little better than wpg though.

    But 2.7wpg in 400 litres is plenty, honestly. I've carpeted glosso in 1.6wpg in 125 litres. Not sure of the lux though. It was 3x T8.

    In larger tank the wpg is even more 'leanient', so anything more than 2wpg is plenty. Generally. If you're using good FL with reflectors that is.

    What is your lighting exactly, out of interest?
     
  9. stevet

    stevet Member

    Messages:
    80
    Location:
    London
    i have just edited my earlier post with some more detail. The three 55w lamps are giesemann floraplus lamps, one interpet 55w daylight plus and and interpet 55w triplus.
     
  10. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    You may have a great way then to solve the entire problem of the CO2. You could pipe the CO2 into the wet/dry filter area. This would then function as a built in CO2 reactor. You would need to check you rubber seals regularly though. Another option may be to close this air inlet, assuming that doesn't cause pressure problems.

    You won't have oxygen problems unless you're over-stocked. Pearling does not mean your plants aren't producing O2. It is due to localised O2 saturation around the plant leaves.

    I'd think you may be best simply having a CO2 reactor after your filter and leave the wet/dry bit as it is. Is there an air outlet to the wet/dry chamber, or just an inlet? If there's no outlet then there's nowhere for the CO2 to gas off to and the previous comments about the partial pressures of CO2 in the wet/dry chamber will still hold, even if extra air is being sucked in.
     
  11. fishgeek

    fishgeek Member

    Messages:
    117
    Location:
    west sussex
    if the eheim filter has the ability to lose a gas it will leak

    thats what my logic says anyway, so the air inlet must be a one way valve, that still leaves all the CO2 added to the system in the sytem whether dissolved in water or as a gas

    i am just being dense or thinking too simply?

    andrew
     
  12. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    No, that's exactly what I'm thinking too. Unless we're both being dense... :lol:
     
  13. beeky

    beeky Member

    Messages:
    879
    Location:
    Chippenham, Wiltshire
    I found some pictures on the eheim web site which may help, although I found them too small to be of any use. I would have thought that if they were sealed then no oxygen would be able to enter the chamber and thus would render them no different to a normal canister filter. If they don't have a one-way valve then they may only leak if turned upside-down, but they would have to be under pressure somewhere in order to get the water back up into the tank. So...er...I don't know....

    Here's the link:
    http://www.eheim.de/eheim/inhalte/index ... 27566_ehen
     
  14. stevet

    stevet Member

    Messages:
    80
    Location:
    London
    Someone on another forum suggested that i couldnt possibly be outgassing all of my c2 as he used a massive sump system and believed he would outgas far more than i would ever with my piddly eheim - yet he still maintains acceptable levels of co2 in his tank! Though it has to be said he uses an inline reactor?!

    Maybe then the carbo plus system is just bad and does not do what it says on the tin?! I believe Roger Miller produced a forum entry about carbo plus in 2001 in which he states the cathode/anode reaction used by carbo plus is based on very shaky understandings of this chemical reaction. He felt SOME co2 would be produced but that the majority of the gas produced would be Hydrogen or even oxygen!? It also chews through Kh leaving a horrible crust on the metal plate of the device.

    The eheim air inlet is not one way - it can sometimes fill with water if there is a problem with the filter and so when air is not being sucked into the cannister it is possible it could act a pressure release valve and outgas co2? The eheim wet/dry acts in a cyclical fashion drawing in water to trckle over the media and expose to o2 and then releasing it - then starting the process of drawing in water and o2 again. thus the water comes out of the outflow in 30 second long spurts rather than as a continuous stream.
     
  15. stevet

    stevet Member

    Messages:
    80
    Location:
    London
    Seems this was the exact problem. Received and installed my new D-D co2 pressurised system and diffuser tonight, within 2-3 hours the drop checker reagent was turning to greeny blue and then on to green. Also some of my plants had started pearling - which is good news! Was totally surprised by how blatently that carbo plus thing does not work!! Dramatic change in plant behaviour after only one evening of pressurised co2. I feel quite ripped off by zac (peddlars of the carbo plus crap). I have it set at about 1 bubble per second at the moment. Wonder how long the 600gm bottle will last at 1bps?

    One query though - the solenoid on the regulator gets very hot! Has anyone else noticed this on their solenoids?
     
  16. bugs

    bugs Member

    Messages:
    356
    At 3bps my 600g cylinder would last about 1 month. On that basis it should last you 3 months if our bubbles are similar size...

    Solenoid's do get very hot. I made a bracket for mine so I could mount it in a place where it would not do any damage. I did try one of the solenoids that claims to stay cool but it didn't so I returned it.
     
  17. stevet

    stevet Member

    Messages:
    80
    Location:
    London
    Thing that concerns me is that the solenoid is actually part of the regulator itself (part of a co2 kit) and so is, by sheer dint of being very close, heating the regulator up.

    I am not sure that is the best thing to do with something that is keeping 100 odd psi of co2 under control?

    Oh and did you get any co2 dump problems as the cylinder nears exhaustion?
     
  18. milla

    milla Member

    Messages:
    241
    Location:
    Leeds
    Yes, you do get co2 dump on disposable cylinders.

    I wouldn't worry about heat issues with the regulator and solenoid, D&D have sold lots of these and i have never heard of any heat issues - i am sure they would have been mentioned all over the forums if this was the case.

    I purchase replacement cylinders from Machine Mart £8.50 for 600g
     
  19. stevet

    stevet Member

    Messages:
    80
    Location:
    London
    anything that can be done about co2 dump then? I cant tell as i only have the one guage which only reads 1 bar (manufacturers recomended 'coarse valve' pressure) now so if it loses pressure then i am not sure ill be able to tell?
     
  20. Matt Holbrook-Bull

    Matt Holbrook-Bull Founder

    Messages:
    963
    Location:
    Dorset, UK
    even systems with a main pressure gauge wont tel lyou much more.. because of the way CO2 behaves under pressure.. its contained pressure will always be the same right until the last minute, only then will either gauge start to drop.. which means that you only really need one anyway..

    your operating pressure (the 1bar) will drop slowly as the tank starts to run out.. this is the sign you need to refil/exchange. dont bother waiting for it to run out, as youll probably get a dump as the regulator fails to hold the lower final pressure.
     

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