The Planted Tank Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
56 Posts
Discussion Starter · #1 ·
I have been trying to fight off a light hair and brown brush algae problem. Most things I have read mention low Co2 can contibute. I inject Co2 controlled by a Pinpoint Ph meter which reads a Ph of 6.7. It is a 54 gallon and based on the Ph/KH chart I should have plenty of Co2. But to make sure I obtained a drop checker and 4dkh standard. I ordered an API ph kit for the indicator. After receiving the kit, just for couriosity, I checked the Ph with it. fully expecting it to be in the ballpark of the meter. However it is way off. it is reading about 7.2 while the meter reads 6.76. I then checked the tap water, meter reads 7.14 and kit reads 7.4-7.6. I calibrate the probe regularly and it always calibrates well. I noticed my drop checker with 4 drops of bromethly blue from the kit and the standard is still blue after 3 hours. What could be wrong? Is the API kit way off or is my tanks ph being lowered by drift wood, aged substrae (about 8 years old now) etc. If it is being lowered by other things in addition to Co2, if I add Co2 till my drop checker turns green it would probably lower the ph to 6.0-6.2 or so. That would be way to low. What should I do?
 

·
Registered
Joined
·
2,709 Posts
Are you fish and plants healthy? If so, don't worry so much about decimals. After you relax a bit, consider alternative, or simply more, possibilities. I'm sure you'll get lots of suggestions from others, soon.

One bit I noticed is you say you calibrate your probe regularly. How old is the probe? They deteriorate over time.

Is your API kit fresh? There is a date code on the box.
 

·
Registered
Joined
·
496 Posts
first of all through the ph kh chart out the door, its not accurate because the results are contaminated from other things in your water
the probe works much better if its in a current
i set my on off points by my drop checker
if its blueish green at all i turn the control points down slowly increasing co2 over days
till i find a nice balance

id say that probe is more sensitive then the ph test in its ability the sense ph from co2
also i wouldn't assume the ph would go from 6.7 to 6.0 to turn drop checker green
 

·
Registered
Joined
·
56 Posts
Discussion Starter · #4 ·
Are you fish and plants healthy? If so, don't worry so much about decimals. After you relax a bit, consider alternative, or simply more, possibilities. I'm sure you'll get lots of suggestions from others, soon.

One bit I noticed is you say you calibrate your probe regularly. How old is the probe? They deteriorate over time.

Is your API kit fresh? There is a date code on the box.
The probe is about 5 years old. I have read, probes usually only last about two years, but mine is still going. I calibrate each month or two and it always reads great and does not drift. I guess I have k\just had good luck with the probe.
 

·
Registered
Joined
·
379 Posts
are you calibrating the probe with new, unopened buffers? 10 buffer especially expires about 30 days after it's opened because it absorbs too much CO2 from the air. Also, tank water in your buffer, or any type of contamination can throw off the calibration which you won't notice if you're comparing it to the same buffer you calibrated with.

Test kits can be off too. I hate pH test kits because they always seem to be off, but some people use them quite successfully.
 

·
Registered
Joined
·
56 Posts
Discussion Starter · #6 ·
first of all through the ph kh chart out the door, its not accurate because the results are contaminated from other things in your water
the probe works much better if its in a current
i set my on off points by my drop checker
if its blueish green at all i turn the control points down slowly increasing co2 over days
till i find a nice balance

id say that probe is more sensitive then the ph test in its ability the sense ph from co2
also i wouldn't assume the ph would go from 6.7 to 6.0 to turn drop checker green
Seting the on/off points to the drop checker is an intresting idea. And yes the Ph/Kh chart is not the way to go. I was just a little worried that after 3 hours the drop checker was still blue, combined with the fact the test kit was giving me a ph higher than my monitor, I began to question if I had enough Co2. If something in my tank was lowering my PH to begin with, it seemed possible that to get it down to my set point it would take very little CO2.I Just didnt expect the test kit would read that much diff then the meter
I will move th probe into the current more and see if it changes some. thanks for the tip
 

·
Registered
Joined
·
56 Posts
Discussion Starter · #7 ·
are you calibrating the probe with new, unopened buffers? 10 buffer especially expires about 30 days after it's opened because it absorbs too much CO2 from the air. Also, tank water in your buffer, or any type of contamination can throw off the calibration which you won't notice if you're comparing it to the same buffer you calibrated with.

Test kits can be off too. I hate pH test kits because they always seem to be off, but some people use them quite successfully.
I use the one use packets 7 and 4. I thought about ordering the bottles once but heard just what you mentioned that after opening they begin to lose accuracy after a while, so I just go with the packets to be safe and I make sure they have not expired.
I think it is strange however that the probes has lasted this long. a whlie ago in a conversation with someone from Geen Leaf aquatics about co2 bubble counters, we began talking about how I controlled my CO2 and he was impressed that it was still working well. He did say however that he has noticed from others that the Pinpoint probes seem to last longer since they are filled with more fluid inside and they do not dry out as quickly as others. But I don't really know, its the only one I have ever owned
 

·
Registered
Joined
·
379 Posts
Probes are finicky, they can last for 10+ years or last for 2 months even among the same brand/models. There are dozens if not more variables that can affect a pH probe so it's hard to give an accurate determination of when a probe needs replaced. I say if it's still working, then don't replace it.


Another thing to consider is the ionic strength of your tank. If it is very soft/mineral poor water, then pH probes have a hard time getting a reading and it can take 15-20 minutes before the reading stabilizes. In contrast, a buffer is very high ionic strength, so a reading stabilizes very quickly. Ionic strength specifically refers to charged constituents in the water, so even if the water is full of material, if it's not charged, the meter will have trouble reading it. This is not a problem when dealing with test kits because the mechanism is completely different.
 
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top