Frozen calibration solutions - General Aquarium Plants Discussions - Aquatic Plant Central

Go Back   Aquatic Plant Central > General Interest Forums > General Aquarium Plants Discussions

General Aquarium Plants Discussions Discuss aquarium plants, aquatic environments, aquarium lighting, aquarium filters, aquarium backgrounds, and other aquarium topics.

Reply
 
LinkBack Thread Tools Display Modes
Old 02-12-2006, 11:52 AM   #1 (permalink)
 
Join Date: Feb 2006
Posts: 111
iTrader Ratings: 0
dogdoc is a regular member
Default Frozen calibration solutions

This will be somewhat long. Please bear with me.

I recently setup a pressurized CO2 system that includes a Milwaukee SMS 122 pH controller. Calibrated it at setup, and everything seemed o.k. Today was the day for my first weekly re-calibration. I rinsed/cleaned the probe as directed with distilled H20 and alcohol, rinsed again and placed the probe in my calibration solution. It read 7.6 in the 7.01 solution. I adjusted the calibration and rinsed it and placed it back in the tank. It then read 5.9 pH.

I don't think this can possibly be right. First, it would give me a CO2 level of about 90 ppm and none of my fish are at the top or gasping. Second, I used my test kit and got a pH of 6.6 on the tank water.

I had used the packet of 7.01 solution that came with my controller for the original calibration. But today I used a bottled 7.01 solution. I'm concerned because the bottle arrived frozen solid when it got here a couple of months ago. The retailer said it should be fine after thawing.

So my questions are:

Should I just toss the bottled solution? I don't know if I can get another one anytime soon that won't also arrive frozen. Just too darn cold here.

Second, what should I do in the meantime? I matched the pH controller up to what my test kit reads as a starting point. I definitely don't want to overdose my CO2 and kill my fish, but I don't want to underdose it either.

Any help or advice appreciated.
dogdoc is offline   Reply With Quote

Advertisement [Remove Advertisement]
Old 02-13-2006, 10:28 AM   #2 (permalink)
Senior Member
 
titan97's Avatar
 
Join Date: Feb 2005
Location: Charlotte, NC
Posts: 348
iTrader Ratings: 8
iTrader Positive Rating: 100%
titan97 is a regular member
Default

I don't have the same pH controller, but here are some thoughts:

If it uses a glass bulb for making the pH reading, you should always keep it wetted. A dry bulb will cause erratic readings. There is no way to work around this, and once a bulb is dry, it takes a long time to re-hydrate, if a all.

Most pH meters/controllers need a minimum of 2 solutions for a good calibration. You can obtain calibration solutions of 4.01 and 10.0 very easily. Remember that the pH probe is measuring the mV potential between itself and the water. This potential is then converted to a pH number. The mV plot is linear while the pH plot is logrithmic. You need an accurate calibration if you want an accurate pH reading. Using 2 (or even 3) solutions is best.

Make sure the pH probe isn't near any source of electricity, like fluorescent lamp ballasts or filter pump impellars/housings. The magnetic/electric field of these things can drasticly change the pH reading.

Most pH probes are only good for 2 to 5 years. Some of the higher end models I use in my line of work are only rated for 6 months or less. You might need a new probe. Obviously, this is a last resort.

If you check you tap water with the test kit and with the pH controller, do they match up? Do this far away from any electrical source if possible.

As far as CO2 dosing goes, many folks just crank it up until they see the fish begin to stress, then back it down a little. Actuall ppm of CO2 can be very misleading. Just look at your tank and use that as an indicator.

-Dustin
titan97 is offline   Reply With Quote
Old 02-13-2006, 02:52 PM   #3 (permalink)
Senior Member
 
dennis's Avatar
 
Join Date: Mar 2004
Location: Leverett, Mass
Posts: 2,988
iTrader Ratings: 47
iTrader Positive Rating: 100%
dennis is a regular member
Default

Dustin,

All your points are certainly correct, obviously as you deal with this stuff for a living However, I have the SMS 122 and it is common practice to calibrate with only the pH 7.01 solution. I belive it even stats that in the directions, as long as you are using it in freshwater of mid pH ranges.

See another thread here

Reading through that I wonder 2 things. First, can the slope change over time, as in a few years? Second, the dial on the front of my SMS122, the part you turn to select you pH, has always been a few points off. I assumed it was just a poorly squashed on knob but know I wonder?

Also, the SMS122 has a +/- .2 accuracy, which can vary the CO2 levels a bit when discussing CO2 levels.

Fish stress is not necessarily an indication of high CO2, it can also mean low O2. Remember the CO2 does not displace O2 in water so technically you could have 100% saturation of both, or only one. In my opinion the best way to describe setting CO2 levels based on fish stress levels would be..."Increase Co2 levels until you observe fish stress and intense pearling at the same time, then back off on the CO2 rate until fish are fine" By intense pearling I don't mean a few bubbles rising from a cut leaf or a little on the bottom of some rotala leaves but lots of bubbles everywhere This woudl insure that fish stress was due to CO2 and not low O2.
dennis is offline   Reply With Quote
 
Old 02-13-2006, 07:48 PM   #4 (permalink)
 
Join Date: Feb 2006
Posts: 111
iTrader Ratings: 0
dogdoc is a regular member
Default

I guess what it comes down to for me, is which to trust right now.

I can use my tank water and an AP test kit and calibrate off that for the moment until I can get new calibration solutions.

Or I can use the calibration solutions that I have, which arrived frozen solid, and seem to give me weird readings.

I just don't know which to trust, but the tank water and pH test seem to jive better with reality.
dogdoc is offline   Reply With Quote
Old 02-13-2006, 09:58 PM   #5 (permalink)
Senior Member
 
dennis's Avatar
 
Join Date: Mar 2004
Location: Leverett, Mass
Posts: 2,988
iTrader Ratings: 47
iTrader Positive Rating: 100%
dennis is a regular member
Default

I highly doubt that your AP kit is accurate. Maybe, but I doubt it.

Freezing of tje test kits should have no impact on their use as long as they were not frozen when you used them adn that they were at room temperature. I to cleaned my probe as discussed in the sticky at the top of the Equipment Forum. I found that I got wacky readings after also. I belive one needs to soak the probe in RO/DI water for several hours, over night would probably be better. I bet your readings would be more accurate. The little glass bulb at the end of the probe is some kind of thin permiable membrane with water in it. soaking it in alcohol would probably pull some of that moisture out thus the need for th elong soak in water afterwards.

I could be wrong about that though. Maybe Dustin knows?

Try doing the windex test, soaking it for a while then recalibrating again. I doubt your APC kits is accurate enough to trust.
dennis is offline   Reply With Quote
Reply


Aquatic Plant Central > General Interest Forums > General Aquarium Plants Discussions > Frozen calibration solutions

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Aquatic Plant Forum Replies Last Post
Need help making calibration solutions ElectricHead South Western Ohio Aquatic Plant Enthusiasts 5 01-31-2006 04:17 PM
Dosing traces in solutions Happy Camper Fertilizing 6 01-19-2006 12:53 AM
autodoser & combining solutions mintygreen Fertilizing 9 06-14-2005 10:46 AM
pH Controller Calibration Jim Equipment 4 04-30-2005 02:49 PM
Frozen plants MissMinerva General Aquarium Plants Discussions 10 01-08-2005 05:51 PM


All times are GMT -8. The time now is 09:54 PM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

Search Engine Friendly URLs by vBSEO 3.6.1