• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Unknown algae - please help?

This simple - just put the meter in the bag:

5jxi88.jpg


Did the PH 7 calibration first, needed to lower the value 0,8!
After this the PH 4 fluid didn't need a correction.... Now trying to find KCl which is harder to get then I thought :(
 
thanks for the Ebay link! isn't the price difference compared to non-Ebay stores suspicious? Could there be a difference in quality, or is the quality good enough for my usage?
 
Hi,
There is always a suspicion, but the differences may have more to do with the cost of overhead by the different vendors, or other factors. If you live in a place that has snow, KCL is just road salt which has a lower purity. If it's sold as food grade then it should have a higher purity (100%), but again, this is just salt that you can put on your salad with a bit of olive oil and vinegar. Tastes great, is less filling and causes less hypertension than ordinary table salt (NaCl). So maybe it's the other guys who are overpriced?

Cheers,
 
ceg4048 said:
For a more complete analysis I always suggest that pH readings be taken at regular intervals before, during and after the photoperiod. The pH readings give us an idea of how the gas is behaving, NOT what the absolute value of the CO2 is. I suggest you take pH readings at 30 minute intervals from the moment the gas goes on till the moment it goes off. Then we can look at the rate of change of acidity and evaluate from there.
Click to expand...

Although I'm starting up a new tank, I've done some measurements during the day with the pH meter attached like this:

9764022002_777f4c745d.jpg


What do you think of the following readings for my new tank?

First measurement (pH 7.8) is being done after 60% water change (pH 8 tap water). I have calibrated the pH meter before starting the test.

11:00: pH 7.8 - CO2 ON
11:45: pH 7.4
12:30: pH 7.2
12:45: pH 7.1
13:00: pH 7.0
14:00: pH 6.9 - Lights ON
15:00: pH 6.8
15:30: pH 6.8
16:00: pH 6.8
20:00: pH 6.7 - CO2 OFF
20:30: pH 6.8
21:00: pH 6.8
21:30: pH 6.9
22:00: pH 7.0 - Lights OFF


Tank is running exactly one week now, doing every second day 60% water change. No signs of algae yet....
 
Hi,
That pH profile look OK to me. That you were able to drop the pH almost a full unit by lights on is always a good sign. Even better is the fact that the pH does not drop too much farther throughout the remainder of the photoperiod, so that means the risk of CO2 toxicity is low.

I would have preferred the first reading to have been taken without the water change. That's because tap water has CO2 in it so the profile is distorted by the new water. So this data is valid for water change day, but what does it look like on non-water change days? Hopefully it's very similar. If not, then you may have more tweaking to do.

Isn't the probe a useful tool? Aren't you glad that you don't have the messy liquids to deal with any more?

Cheers,
 
I'm very happy with this probe; useful, accurate and way more faster then doing a drop check.

The only think that worries me is that after calibration to exactly pH 7.0 the meter displays pH 7.1 or even pH 7.2 after 2 or 3 days putting it back in the pH 7 calibration liquid. Seen this a few time now with more or less then 3 times doing a measure after this calibration. Isn't this strange?

I already thought that the water change could have influence on the readings. Next week I will do another measure (same setup) without water change.

Thanks!
 
Well it ought not to drift so much. Try storing it in the salt fluid or calibration fluid instead of leaving it in the tank, and see if this makes a difference.

Cheers,
 
ceg4048 said:
The whole idea is to force the probe to read 7.0 and 4.0. If you add water to the fluid, you will change the pH and will distort the calibration.

Just stick the probe in the 7.01 fluid and wait a minute or so for the reading to stabilize and to stop moving around. For this model you should have received a small screwdriver. If the reading is not exactly 7.0 then use the screwdriver and turn the little calibration screw which is just below the display. It should be labeled as "7.0" or something like that.

Then, rinse the electrode. You can use tap water to do this.

Follow the same procedure with the 4.01 fluid. Allow the reading to stabilize and if it does not read exactly 4.0 in the display the turn the screw labeled "pH4/10" (or whatever).

That's it!



Cheers,
Click to expand...
Sorry to jump in but i just have a quick question.
Is it necessary to calibrate the pen to both ph7 and ph4 or just the closest to your reults, eg ph7?
Just want to clarify before re-calibrating my meter, the instructions are slightly vague with it but it intimates only calibrating using the nearest calibration fluid to the ph to be measured.....i know that sounds a bit daft :confused:
I have bought both ph calibration fluids.


Cheers,
Ady.
 
Hi Ady,
Really, for these probes you need a two point calibration. If you calibrate only at one point then you may have errors as the value moves away from that point. 7 is not really your nearest point. It is the neutral point, so what they are saying is that if you measure things that have a high pH then you need to use the 7 and the 10 so that the probe is more accurate and has a more linear response in that direction. If you measure things in the acidic range then you need to use the 7 and the 4. It's very difficult to have a probe that is accurate and consistent from 4 to 10. That's just too wide a range, so the best thing is to use the 7 and then select the nearest calibration fluid nearest your usual range, either high or low.

Cheers,
 
Thanks Clive.
These are the instructions:
BpPyh2B.jpg

You can probably see why I asked.

I have re-calibrated my meter now to both, it was a little out but spot on now :)
Got all I need to keep me accurate for a while!
Cf3hnvb.jpg


Thanks,
Ady.
 
Hi Ady,
Yeah, that's weird. It sure looks like they are saying to use a single point calibration. Anyway, glad the numbers look goo now.

Cheers,
 
You must log in or register to reply here.
Back
Top