Re: [APD] CO2 and pH control

[Gordon and Susan Watkins <gwatkins at ritternet_com>]

Thanks again for the practical suggestions David. I think I'll start by 
bypassing my trickle tower, an easy change, and see what happens. I'll 
report back on my findings. By the way, my corner overflow does have a 
home built Stockman standpipe which keeps the overflow chamber almost 
full and reduces turbulence there. My sump also has a tight fitting lid 
when the tower is removed. I'm a little reluctant to give up my sump 
entirely as I have an auto evap control system there. I'm a little like 
you in that it irks me not to be able to control the pH more 
discretely,  particularly after spending $$$ on a high-tech system, 
something I usually avoid. I'll let you know how things progress.

Gordon

David Grim wrote:

>Gordon wrote:
>  
>
>David,
>    I really appreciate your taking the time to provide such a thorough
>response to my question.
>
>    Yes, you are correct in assuming that this was once a reef tank. And
>you're also correct that my filtration system is probably overkill for a
>29 gallon tank, but I like to tinker - what can I say? The filter is a
>modified RDP filter with a bioball tower added (no current RDP
>fiunction) There is a 3 gallon glass chamber filled with Dupla bioballs
>beneath a perforated drip plate covered with poly fibre quilt batting as
>a coarse filter all sitting on top of the sump. The tower has a tight
>fitting lid. I debated adding the trickle chamber but after reading
>George Booth's articles on the subject, concluded that trickle filters
>were not a significant source of CO2 offgassing, although I'm guessing
>that's a debatable pointn.
>
>    The tank upstairs has a corner overflow and because of its location
>(built into a living room wall) I don't have many options besides the
>remote filter. I could remove the tower and just use the sump but I
>would still have the waterfall effect in the piping.
>
>    The tank is covered with a home made cover with 2 PC bulbs suspended
>2 inches above the water. The ends of the cover are open for ventilation
>so I would consider it an open top tank.
>
>    HOB filters are not an option nor are canisters unless they are used
>at the sump.
>
>    The SMS122 controller is new and I calibrated it to 7.2 upon setup a
>week or so ago. The reading correlates with chemical pH tests so I'm
>confident in its accuracy.
>
>    Regarding the AAS atomizer, it's really just a misting wand for a
>drip irrigation system and while it's a handy way to have inline
>injection, I question its efficiency. Do you think I could gain anything
>with say an external Aqualogic reactor or one of the membrane types or,
>with the amount of offgassing it sounds like I have, am I doomed to have
>an inefficient CO2 system?
>
>    On the other hand, others have pointed out that if I've got good
>plant growth and happy fish, which I have, I should be satisfied and
>quit worrying about pH levels. Am I trying to micro-manage too much?
>  
>
>
>Gordon,
>
>My experience with the 240 gallon planted tank (Oceanic 240 reef ready) with
>wet/dry filtration tells me that the more water movement you have the more
>off gassing of CO2 you have. I have not read George's articles on it. My
>experience is purely anecdotal. All I can say is that conditions being
>constant except going from wet/dry filtration to canister filtration in a
>planted tank, with the resulting decrease in water
>movement/sloshing/splashing/cascading/bubbling, etc., the pH of the tank
>lowered to my target level, and the controller cycled off for longer
>periods. I just plain used less CO2 and the pH was easily controlled vs.
>using CO2 in a wet dry with the controller on all the time. This using the
>same internal CO2 reactors with both setups. Tinkering is great. That is how
>I set up a completely automated water changing system that services a 265,
>240, 75 and 120 gallon tank.
>
>If everything is cool and you like the plant growth, etc, then you could
>just leave it status quo. I never liked not being able to keep the pH where
>I wanted it, because it never seemed a problem for other planted tank
>keepers. And my water here in Atlanta comes out of the tap with a GH and KH
>of less than one. The best I did with the 240 planted with wet dry
>filtration was 6.8-6.9, where I wanted to have it a bit lower, like 6.5-6.6.
>This was with two reactors, each with a 20# CO2 tank feeding it. Assuming
>that there is a relationship between water movement in a wet dry and CO2
>loss, there are a few choices for you:
>
>Lessen water agitation within the tank and the  wet/dry system: I pulled the
>bioballs out of the wet dry and plumbed a barbed fitting under the tower
>cover and attached a piece of vinyl tubing which made the water enter the
>wet/dry enter below the water level in the sump, which lessened the
>splashing. This removed the bio filtration of course, but it is really not
>needed in a planted tank IME, and eliminates another source of water
>agitation and possible off gassing. You could add a submerged sintered glass
>media or an air driven Hydrosponge in the sump to have some backup bio
>filtration if you want it there for peace of mind. I use Hydrosponges in the
>sumps of my bare bottom Discus tanks. I covered all open areas of the tank
>and the wet/dry to try to keep as much gas from leaving that way. Point the
>water return downward to reduce any surface agitation. All this should keep
>CO2 in the water longer.
>
>Add an in-tank CO2 diffuser: The Dupla unit I mentioned would be good for
>your tank, unless the combined volume of your sump and aquarium are more
>than the unit is rated for. Just keep the small size of the tank in
>consideration, as aesthetically a large in tank unit might be ugly. The AAS
>in line unit just doesn't work well enough.
>
>Do both of the above and you may see improvement.
>
>There is another option for you where you can pull the wet dry altogether,
>but keep the same overflow and location of the filter (in your basement):
>You can use a closed type canister filter with an in-line pump to return the
>water from the basement to the tank above. Look at his URL:
>http://www.drsfostersmith.com/Product/Prod_Display.cfm?pcatid=3662&N=2004+22777
>
>Your prefilter will work the same, except now there would be a constant
>level of water in the tank. Your corner overflow would be filled with water
>to the top. The water level is determined by the level in the tank now and
>not the level in your sump. Your setup is now a closed water loop like a
>canister filter setup is, except the overflow plumbing from the prefilter is
>now completely full and the water is not splashing anywhere and there is no
>CO2 loss from water agitation. Evaporative loss is now shown in the tank
>water level and not the sump water level. You could probably inject CO2 into
>the filter intake and not need an internal reactor with this setup since you
>have eliminated the agitation.
>
>This method is not cheap, but would probably solve your problems and
>wouldn't interfere with the installation setup of the tank itself.
>
>Regards,
>Dave
>
>
>
>
>
>
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>  
>
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