Using ORP meter

[zek]

I started using a YSI Ecosense ORP pen meter last night.

1st use about 90 minutes after feeding I got a cess pool reading of 180-190. It was quite a shock as I never get ammonia, or nitrite readings. I've never had health issues since I started up in spring 2006. I have not turned on the UV this spring as the water is clear and after 2 SP treatments covering ~50% of the pond each time the winter algae was knocked back and I have a light fuzz the koi maintain.

This morning the reading was 302 -304 before I fed. Are swings of this magniture possible in 10 hrs?

Another thing, sometimes the meter drifts slowly dropping a few points at a time. Other times it locks right, like in the solution and in tap water. This AM it locked on quick. Is it normal to have to wait for the meter to settle in order to obtain a reading at times?

[MCA]

I can only relate my experience. I had a handleld Hanna and gave up on it. I use a Pinpoint unit that I can clean and calibrate with 400mV solution. I keep the probe also wet by mounting it in the skimmer.

With a calibrated meter that has time to settle down, you may see ORP changing some during the day. If you are getting serious changes, and the meter is OK, then consider that you may be seeing the pH rise and fall. The lower the pH, the higher the ORP...all other factors being equal. ORP is a measurement of the potential (or ease) of moving electons through the water. That is why we measure in mV. Why do car batteries us acids as the solution around the plates? It is easier to move electorns in acidic solutions compared to base solutions.

So why the rise and fall of pH? Two things may be happening. First is low KH in the water. The second is the plants (including algae on the walls and free swimming). Please give off O2 as a result of photosynthesis during the day. But at night they respire CO2...which goes into solution as carbonic aicd...which can put down the pH...and increase ORP.

So with a calibrated ORP meter, check the ORP, pH, and KH in the morning (when ph should be lowest and ORP higherst) and at dusk (when pH should be highest and ORP lowest). See if you see a pattern.

[zek]

Thanks, PH dropping over night from the algae causing an increase in ORP makes sense. I have BS, calcium carbonate and Epson salt on hand to lock the PH and will see how it changes the next few days. Also want to test before and after feeding.

What problems did you have with the Hanna? I'll likely have the same issues.

[JasPR]

right, check your oxygen reading before and after feeding and check your pH in the early morning and early evening.
The point of an orp reading is to get a glimpse of the worst ORP reading in the pond and not the best reading for bragging rights. In that regard, you WANT to get a reading when your oxygen is at it's lowest and your pH is at it's highest and lowest. You should NOT assume that pH is always the same but if , in your testing/investigating, you do see wild swings in your pH this is another conversation and maybe more important than your ORP reading.

In all modesty, I brought ORP to the ponding hobby here on the net, some 13 years ago now. And I now have mixed feelings about doing it as it has become THE most misunderstood test in the koi hobby.
I will mention this again - an ORP reading is both a relative reading and a trend reading. It is NOT a reading like temperature. ammonia presence or even pH. The number can not be interpreted by the readngs from others and only general statements can be made about it. And although there are definite BAD readings and VERY GOOD readings, there are just as many illusionary readings. Take ORP readings with a grain of salt until you have logged a trend line for your pond against a backdrop of oxygen , temperature and pH.
a word to the wise--- JR

[farne230]

Originally Posted by MCA

I can only relate my experience. I had a handleld Hanna and gave up on it. I use a Pinpoint unit that I can clean and calibrate with 400mV solution. I keep the probe also wet by mounting it in the skimmer.

With a calibrated meter that has time to settle down, you may see ORP changing some during the day. If you are getting serious changes, and the meter is OK, then consider that you may be seeing the pH rise and fall. The lower the pH, the higher the ORP...all other factors being equal. ORP is a measurement of the potential (or ease) of moving electons through the water. That is why we measure in mV. Why do car batteries us acids as the solution around the plates? It is easier to move electorns in acidic solutions compared to base solutions.

So why the rise and fall of pH? Two things may be happening. First is low KH in the water. The second is the plants (including algae on the walls and free swimming). Please give off O2 as a result of photosynthesis during the day. But at night they respire CO2...which goes into solution as carbonic aicd...which can put down the pH...and increase ORP.

So with a calibrated ORP meter, check the ORP, pH, and KH in the morning (when ph should be lowest and ORP higherst) and at dusk (when pH should be highest and ORP lowest). See if you see a pattern.

MCA, can not agree more, in my case PH swings from 6:00am (representing night time) no sun no algae asleep, LOW PH 8.4; at 7:00PM (daytime, lots of sunlight), algae alive and happy the PH is up to 8.8. Although my orp fluxuates in 24 hours very little 10 to 30ppm. Also note, orp probes need constent calibration and cleaning, after a week or so it may drop 50ppm or more after calibration and cleaning. Temp has some to do with orp and ph too. Right JR, DO reading do effect ORP.
Bob

[zek]

Originally Posted by JasPR

right, check your oxygen reading before and after feeding and check your pH in the early morning and early evening.
The point of an orp reading is to get a glimpse of the worst ORP reading in the pond and not the best reading for bragging rights. In that regard, you WANT to get a reading when your oxygen is at it's lowest and your pH is at it's highest and lowest. You should NOT assume that pH is always the same but if , in your testing/investigating, you do see wild swings in your pH this is another conversation and maybe more important than your ORP reading.

In all modesty, I brought ORP to the ponding hobby here on the net, some 13 years ago now. And I now have mixed feelings about doing it as it has become THE most misunderstood test in the koi hobby.
I will mention this again - an ORP reading is both a relative reading and a trend reading. It is NOT a reading like temperature. ammonia presence or even pH. The number can not be interpreted by the readngs from others and only general statements can be made about it. And although there are definite BAD readings and VERY GOOD readings, there are just as many illusionary readings. Take ORP readings with a grain of salt until you have logged a trend line for your pond against a backdrop of oxygen , temperature and pH.
a word to the wise--- JR

Thanks JR, It was a little disconcerning seeing the read last night, but it doesn't do much for me without longer term trend analysis. I understand ORP isn't going to be the end all be all, but it does look like it will give a good deal of insight into another level of the pond working.