Questions on CO2 and PH

[beanbean]

i read from a thread inserted long ago in this forum regarding CO2 loss from surface turbulence and KH acting as a buffer.....
My questions are: 1.If i use those liquid PH-down liquids and achieve a stable PH like say 6.8, den i do not have to inject as much CO2 as compared when i did not use the PH-down liquid, in order to achieve a desired PH?? im still caught between using a reactor and diffuser. shld i test my PH and KH levels to track my CO2 content in water? what are some ways to achieve a starting KH of 2 as advised by Vinz ???
2.I've seen some tanks in sam yick which have the outlets of their external filter pointing towards the surface, at an angle in the water, izit advisable for me to do that to counter my "proteined" surface problem?

PS: Vinz, u still need my Java moss?? u msg me long ago bud im still waiting for ur further instructions.....cos another member is asking me for it...thanks

[vinz]

Beanbean, check PM...

[Allen_1971]

Bean Bean,

1) When CO2 dissolves in water, it makes the water more acidic. As such, for a given KH, your ph will reduce correspondingly. If you add PH-Down solutions, it will NOT increase the level of CO2 dissolved... In fact if you do so, you screw up the PH/KH/CO2 relationship. My advise is not to use PH-Down solutions. To increase your KH you can add KH-UP powder, or some sodium bicarbonate.

2) Yes, I believe thats why they point the water flow at the surface.

[geoffrey]

IMHO, adding chemicals to lower pH is different from that done thru CO2. Simply put, adding vinger into water lowers pH, but that does not mean you have sufficiently needed CO2 in it.

The direction you want to point your outlet nozzle depends on lot of factors, such as whether there are plants in the way of the outlet and as you have said, do you want it to create tubulence on the water surface...etc.

Some point it against the tank's wall, others 45 deg diagonally across the tank and some may even allow it to flow into the tank like a running tap. You may have to fiddle with it to find what is suitable for you.

[beanbean]

hmm. i understand that adding PH-down won't increase the level of CO2 content in the tank. think i misread what they posted in that thread then.
so can i say that in the night when i cut off the CO2 injection, will PH start to heighten again??
whats a safe amount of bicarbonate to add??? izit the same one that pple use for DIY CO2???den i have it...hehe* 3ft five plan?? around 52Gals without considering gravel,plants,log,and rock?
one last thing, in the thread it says something about using reactor and factors like the speed of the balls spinning, the volume of gases in the reactor including nitrogen bla bla bla from the tank cylinder, does it mean anything that the amount of CO2 i want to inject into my tank may be limited by all this factors because i tried a higher BPS but what happened is that the reactor started 'spitting' out gases which i dunno what...it may be undissolved CO2 due to higher BPS...am i right to say that BPS is sort of like a gauge rather than an accurate measure of CO2 content in the tank?? rather i shld consider the CO2ppm in the tank, which can be measured by testing my PH and KH and finding out the corresponding amount of CO2content?

[Plantbrain]

This might help you:
Plants do not want a certain pH or pH down, they want CO2 to grow well.

That's what that's all about.

KH(the buffer, HCO3 in this case)
CO2(the acid)

The amounts of each determine the pH.

Some slight water surface movement is fine. Just not lots.

Yes, the pH will rise at night if you turn off the CO2. This happens in nature everyday.

For HCO3, bicarb, folks use baking soda. A KH of 2 is okay if you use CO2 but many stay at 3 KH. So you don't need to add much baking soda.

To use CO2, add enough CO2 gas to get the pH down to 6.5 for a KH of 3. For a KH of 2, a pH of 6.3.
For a KH of 10 about 7.1.
That is all you do.

It takes _both_ measurements to determine the CO2, not just pH.

You can use a small powerhead and bubble the gas into the suction side and it will atomize the gas bubble for a simple reactor. You can put a tube to catch it in the tank.

Some folks add a 5cm PVC pipe 25cm long with some bio balls in it right BEFORE their canister filter and bubble the CO2 into the filter's intake. This prevents bubble from entering the filter and dissolves the gas.

Regards,
Tom Barr

[toledosun]

Hey Beanbean,

Just a word of advice. You may want to gradually change away your water before fiddling with the addition of CO2 and such. In the beginning, I used PH minus on my tank. Later, fishes started dying when I started my CO2. Not sure if the death is because my tank was quite new (possible) or because the PH minus was mucking up my readings KH/PH readings (also possible).

All you really need is sodium bicarbonate to increase the KH to about 3-4. After that, use CO2 to bring down the PH. The more CO2 you add, the lower the PH will get so there's really no need to use PH minus.

[bclee]

pH-minus stuff will eat away the KH. Probably, it remove all the KH and caused a pH crash.

BC

[wynx]

----------------
On 3/4/2003 6:00:26 AM

This might help you:
Plants do not want a certain pH or pH down, they want CO2 to grow well.

That's what that's all about.

KH(the buffer, HCO3 in this case)
CO2(the acid)

The amounts of each determine the pH.

Some slight water surface movement is fine. Just not lots.

Yes, the pH will rise at night if you turn off the CO2. This happens in nature everyday.

For HCO3, bicarb, folks use baking soda. A KH of 2 is okay if you use CO2 but many stay at 3 KH. So you don't need to add much baking soda.

To use CO2, add enough CO2 gas to get the pH down to 6.5 for a KH of 3. For a KH of 2, a pH of 6.3.
For a KH of 10 about 7.1.
That is all you do.

It takes _both_ measurements to determine the CO2, not just pH.

You can use a small powerhead and bubble the gas into the suction side and it will atomize the gas bubble for a simple reactor. You can put a tube to catch it in the tank.

Some folks add a 5cm PVC pipe 25cm long with some bio balls in it right BEFORE their canister filter and bubble the CO2 into the filter's intake. This prevents bubble from entering the filter and dissolves the gas.

Regards,
Tom Barr
----------------

Yes, the pH will rise at night if you turn off the CO2. This happens in nature everyday. ??[:0]

I though pH will drop due to the fact that plants and fish are giving out carbon dioxide during the night time when plants are not utilizing C02 but instead of releasing them as well?

I observed that pH indicator actually turned more yellow during night...meaning more C02 in tank after pH level is related to C02 level and I believe that KH is there to act as a buffer to prevent the pH from spiraling downwards.

What do you guys n gals think?

[bclee]

Your CO2 system will add more CO2 than all the organism in your tank can generate.

Usually when the CO2 is turned on, we keep the CO2 at about 20~30ppm. However, the equilibrium CO2 level with the atmosphere is maybe about 0.5ppm (if my calculation is correct). Therefore, if the CO2 system is shut off, the CO2 will escape into the atmosphere. The CO2 contribution by fishes and plants and the micro-organisms are negligible. The CO2 level will drop... pH will rise.

I think it is very unlikely that your pH will drop at night... unless you are running your CO2 24hrs.

BC