PH Changes and PNG Rainbows, I'm Confused

RTR said:
Fish do not and cannot "read" pH. The horror stories of "pH shock" (no such critter) are in fact osmotic shock (osmolarity is very important to fish - they must adjust their physiology when the water differs significantly in osmotic pressure) to manitain their internal chemistry in a stable state. The pH changes from CO2 do not affect the osmotic pressure of the water significantly. If you have TDS equipment you can check this for yourself.
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Nod nod, I feel like you and Dave are smacking my head with a hammer and aren't making a dent :)

As Canuck said, there are discus people who swear . . . [insert here] and I have rainbow people who swear that a drop from 7.4 to 6.6 will outright kill a rainbow and they cite the osmolarity adjustment to justify what they are saying. Now, they are *not* specifically pointing to CO2 injection -- this is just a concern *I* have because of the reaction of my rainbows -- but the conversation seemed to indicate to me that they felt that there is no difference between the drops and rises during CO2 injection plunging a bow into different water (TDS amounts). That doesn't make sense to me, overall, but then I may be reading what they are saying wrong.

Many rainbowfish are quite sensitive to oxygenation, but I have never seen any sensitivity to CO2 supplement, up to at least 30ppm CO2. Do you have a trap bottle or wash bottle between the generator/fermenter and the tank? I would be much more concerned with getting liquid fermrentation products into the tank than the CO2 itself.
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I use a check valve and also blow all the lines out before I add a new bottle. That stuff is heady, btw :)

Nod on the oxygen and that's why I stayed with the Bio Wheels for the planted tank, I need some surface agitation. I am also adding an Eheim 2026 tonight for filteration and current.

My Boesemanis have been moved to a new 75g with no CO2 as yet, so they are out of the DIY tank for the moment. I also have new Boesemani juvies in that new tank with them as well.

I added aragonite and coral to the tank when I set it up on 12/25. My tap water as of 12/28 was pH 7.4, dKH 2, dGH 5. Last night my tank readings were pH 7.7, dKH 2 and I forgot dGH.

I think what I will do, tonight possibly (hubby needs to help as these 20# tanks are HEAVY), is set up the new tanks, add baking soda to bring up my KH to a more stable level and start injecting.

To give the rainbow people the benefit of the doubt, I don't want my pH to go lower than 6.9 (personally, I'd rather it stay at 7). If I can get my KH to 5, that would give me close to 18ppm CO2 and I can work it up, if possible, from there. Will the aragonite and coral dissolve enough at that pH to bring the KH up to at least 5? I can get it to a stable 4-4.5 on the other tank with just crushed coral.

Does this sound reasonable?

If yes, what bubble rate should I be looking for to attain this on a 75g tank? My software gives me a starting rate of 28 bpm, is that good?

Roan
 
You should have no trouble boosting your KH with aragonite and crushed coral.

The bubble count you want is really hard to define. It will vary depending on how well the CO2 is injected and dissolved in the tank. To complicate things even more, the bubble counter on my regulator has a different rate then the bubble counter on my diffuser. I would start out with one bubble (on the regulator for me) every two seconds and adjust from there. Check pH every hour and monitor the decrease.
 
I have followed this thread with much interest (as mentioned to you Roan a 75G with rainbows is my goal - and i too have low kH in my tap). Great questions and answers.

Now it seems everyone agrees that pH swing caused by CO2 injection doesnt (shouldnt) have any negative effects on the fish. Its the ammount of TDS thats important for osmotic pressure.

Now you mentioned you do 50% waterchange 2x a week. If you managed to get the in-tank kH to 4-5 and tap is 2 (i have been following your threads and i think at times you mentioned even lower levels) - wouldnt that create a TDS drop each time you do a water change (and a resulting shift of pH) ?

Its just something that occoured to me - probably unimportant but i thought i'd mention it so maybe someone could comment on this idea and further improve my understanding of the whole planted tank chemistry idea.
 
reiverix said:
You should have no trouble boosting your KH with aragonite and crushed coral.
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Nod :)

The bubble count you want is really hard to define. It will vary depending on how well the CO2 is injected and dissolved in the tank. To complicate things even more, the bubble counter on my regulator has a different rate then the bubble counter on my diffuser. I would start out with one bubble (on the regulator for me) every two seconds and adjust from there. Check pH every hour and monitor the decrease.
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I've got a few of methods I want to try. I purchased one of those Rio 600 VTs that Tom Barr posted about, I have several stone and ceramic diffisuers (which is what I've been using), as well as an Eheim oxygen diffuser that attaches directly to the outflow tube. None of those has a bubble counter. The only one I have is on the Milwaukee regulator set. Probably good or I would just confuse myself even more :)

Okay, I'll start out as you suggestion and monitor the pH like a hawk.

Roan
 
Jay said:
I think RTR is right on.

You might also want to read what I think are some good, not super technical papers here...

www.aquarticles.com/articles/management/Llambi_Water1.html

Jay
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Jay,
Thanks, cramped for time ATM -- have to go out with the family -- so I'll take a boo at that link and the rest of the responses when I get back.

Thanks to everyone for helping me

Roan
 
RA - the check valve in DIY setups may be a bit comforting, but is practically worthless. Check valves fail, a rule of thumb with high validity. Check valves fail fastest in DIY setups. Use a wash bottle between the generator and the fermentor and be sure.

I do breed my DNRs continually, with no bubbles/airstones/surface breaks. I do not have any active aeration devices in any of my tanks. I have not seen the need for such in decades, not even biowheels. With modern filtration (if my old Eheims can still be called modern), and any reasonable current in the tank (which Rainbows do like), it should not be necessary to actively aerate.
 
RTR said:
RA - the check valve in DIY setups may be a bit comforting, but is practically worthless. Check valves fail, a rule of thumb with high validity. Check valves fail fastest in DIY setups. Use a wash bottle between the generator and the fermentor and be sure.
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Okay, what's a wash bottle? I did a search here and only turned up one thread: http://www.aquariacentral.com/forums/showthread.php?t=13466&page=2&pp=15&highlight=wash+bottle
Scared the bloopers out of me. 94ppm? Yikes!

I do breed my DNRs continually, with no bubbles/airstones/surface breaks. I do not have any active aeration devices in any of my tanks. I have not seen the need for such in decades, not even biowheels. With modern filtration (if my old Eheims can still be called modern), and any reasonable current in the tank (which Rainbows do like), it should not be necessary to actively aerate.
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Okay, I hear yah :) Yes, current, I have my magnum shooting water all the way down the 75g and the rainbows are in there all day :) The only fish in that tank are the Boesemani and the Goo obo gudgeons, and that's all that will be in there -- unless I can find another PNG compatible catfish type beastie.

The 36g was too small to get a current current going with them and that may have been part of the problem. I had to cut back on the current because of that and the other fish in there that didn't like as much current. They were hiding all the time.

Gonna try the CO2 in the morning. Just too tired now and I've still 3 more bags of Flourite to wash tonight for the 65g, and water tests tod do on the new 75g and 10g tanks.

Roan
 
A wash bottle is simply another bottle (which can/may be smaller than the fermentation bottle) between the fermentor and the tank. The exit line from the fermentor goes to the wash bottle via a piece of rigid tubing inside the bottle (through the cap) to near the bottom. Some folks add water to the wash bottle (hence the "wash" term), but it is not essential, although it likely is a good thing (I did with DIY). The bottle cap has a second opening, the tube there only barely through the cap, to convey the CO2 to the tank. Any bubble foam or liquid carried out of the fermentor is trapped in the wash bottle. Nothing but gas goes to the tank.
 
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