Overstocked tank - and limits for alkalinity

I have heavily overstocked 30 gallons tank with high
pH swings and low pH average (day: 8.1, night 7.6)
I was wondering if there is a way to help things up
a little without removing animals or moving to a bigger
tank... What are the safe upper limits of alkalinity?
Currently my alk is around 10-11'dK and still my pH
swings is low and swings too much. Enough to say I see
shells the hermit crabs live in dissolve in the water
causing my Ca levels to be above 500mg/l...

I was reading about alkalinity that high levels stabilize
pH in the upper levels but I do not see it happen in my tank.
How one can explain chemistry in my tank ?

"Pszemol" wrote in message
...

I was reading about alkalinity that high levels stabilize
pH in the upper levels but I do not see it happen in my tank.
How one can explain chemistry in my tank ?


Perhaps your room has an excess of CO2??
Can you open a window?
Sounds terribly simple but it worked for me.

Here is a must read:
Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm



--
Toni
http://www.cearbhaill.com/reef.htm

"Pszemol" wrote in message
...
No, I like to keep my windows open an air fresh...
Anyway, high levels of alkalinity buffer should
compensate for CO2 solving in the water, shouldn't it?


No. You can have high alk, and if you pump CO2 into the water, you will
depress the pH. No amount of alkalinity can stop it. Only with good water
circulation, a clean air/water interface, and low CO2 in the ambient air,
can you lessen the effect.

Try this...take a sample of our water early in the morning before the lights
come on, check the pH, then take it outside and blow air bubbles into it
with a straw to aerate it. Now, check the pH again. If it went up, you have
a CO2 problem. If it stayed the same, I'd check the accuracy of my Alk test.

I thought you were up on your Alk/Ca/CO2 relationships? You slippin'? heheh

Kev

"KevinM" wrote in message . com...
I thought you were up on your Alk/Ca/CO2 relationships? You slippin'? heheh

I have to refresh what I read more often... I am getting old ;-)

"Toni" wrote in message ...
Hey-I wouldn't have known except I just went through it.
I started dripping kalk to get the pH back up into a decent range, and it's
now cool enough in SoFla that I can leave a window open and a fan on through
the night.
I made it all the way up to 8.3 today!!

Great!

I have made the air test today, and "eureka"!
My datalog from measurements in the cup of fish tank water taken outside the window:

pH =7.78 = this was the morning low
07:34 11-19-04

pH =7.81
07:35 11-19-04

pH =7.82
07:36 11-19-04

pH =7.85
07:37 11-19-04

pH =7.87
07:38 11-19-04

pH =7.89
07:39 11-19-04

pH =7.91
07:40 11-19-04

pH =7.92
07:41 11-19-04

pH =7.94
07:42 11-19-04

pH =7.95
07:43 11-19-04

pH =7.97
07:44 11-19-04

pH =7.97
07:45 11-19-04

pH =7.98
07:46 11-19-04

pH =7.98
07:47 11-19-04

pH =7.99
07:48 11-19-04

pH =7.99
07:49 11-19-04

pH =8.01
07:50 11-19-04

pH =8.02
07:51 11-19-04

pH =8.03
07:52 11-19-04

pH =8.03
07:52 11-19-04

pH =8.13
08:03 11-19-04

pH =8.05
07:53 11-19-04

pH =8.06
07:54 11-19-04

pH =8.06
07:55 11-19-04

pH =8.07
07:56 11-19-04

pH =8.08
07:57 11-19-04

pH =8.09
07:58 11-19-04

pH =8.10
07:59 11-19-04

pH =8.11
08:00 11-19-04

pH =8.11
08:01 11-19-04

pH =8.12
08:02 11-19-04

pH =8.13
08:03 11-19-04

pH =8.13
08:03 11-19-04

pH =8.13
08:04 11-19-04

pH =8.14
08:05 11-19-04

pH =8.14
08:06 11-19-04

pH =8.15
08:07 11-19-04

pH =8.16
08:08 11-19-04

pH =8.16
08:09 11-19-04

pH =8.17
08:10 11-19-04

pH =8.17
08:11 11-19-04

pH =8.17
08:12 11-19-04

pH =8.18
08:13 11-19-04

pH =8.18
08:14 11-19-04

pH =8.19
08:15 11-19-04


pH =8.21
08:25 11-19-04


pH =8.22 = this is very good!
08:28 11-19-04

The only thing in my experiment which is to be verified is that
the temperature dropped from original 27'C to 15'C (today was quite nice).
How should I correct my reading? I can probably check it myself...

"Pszemol" wrote in message ...
The only thing in my experiment which is to be verified is that
the temperature dropped from original 27'C to 15'C (today was quite nice).
How should I correct my reading? I can probably check it myself...

Ok, my pH-meter has the temperature correction function, so I did
not need to calculate anything - with the measurements of pH 8.24
at 15'C and pH-meter set to 25'C I switched it to 15'c and the
reading jumped to 8.28 right a way. So it looks like the pH is
going way up with the temp going down... Even better for the air test!

"KevinM" wrote in message . com...
No. You can have high alk, and if you pump CO2 into the water, you will
depress the pH. No amount of alkalinity can stop it. Only with good water
circulation, a clean air/water interface, and low CO2 in the ambient air,
can you lessen the effect.

This is so true... I made 2nd test today - this time indoors...
Guess what - my pH lifted very little, from 7.70 to 7.74 and
did not move a bit more over next 30-40 minutes... Not like
yesterday, when during pumping outside air I maganed to get 8.22
So - I was wrong... my indoor air is not fresh!

I need to hook up my skimmer air intake to the outside air somehow.

"Pszemol" wrote in message
...

I need to hook up my skimmer air intake to the outside air somehow.

Do this and your current pH problem will go away. Just be sure to use
oversized tubing so as not to choke off the air too much.

Kev

"KevinM" wrote in message . com...
I need to hook up my skimmer air intake to the outside air somehow.

Do this and your current pH problem will go away. Just be sure to use
oversized tubing so as not to choke off the air too much.

But what about the tank water surface ? It is agitated right now...
Wouldn't it interfere with what I want to do ? The water surface
will be exchanging pressure with the indoor air full of CO2... :-(

"Pszemol" wrote in message
...
But what about the tank water surface ? It is agitated right now...
Wouldn't it interfere with what I want to do ? The water surface
will be exchanging pressure with the indoor air full of CO2... :-(

Most likely not. There is alot more gas exchange going on inside that
skimmer than at your air/water interface. Although I would try to see if I
could get more fresh air in the house, I don't think it will upset your
efforts if you don't. Just hooking your air intake to the outside air will
help some, as it will be constantly pumping fresh air inside.

BTW, what kind of skimmer are you using? What size air inlet on it? (My air
intake is a garden hose)
If your skimmer is, for example, a Skilter (God forbid), I wouldn't expect
much out of it in the way of blowing off CO2. If, on the other hand, you
have something like a AquaC, ER, Beckett, etc...type, something with a
decent sized pump running it, it should have no problem keeping your CO2
blown off.

Kev