ORP Meters

[ILLUSN]

G'Day all,
i've got a ORP meter which I sware is reading wrong over the last few days its gone from 240 to 550 i took the electrode out and washed it and says tap water is reading at 450 and my tank is now 430 ( i do 50% changes weekly with aged rain water).

anyone know of a way i can check if its calibrated? or know of where i can get calibration solutions from?

[sharkbaitnemo]

just wondering what does an ORP meter measure?

[ILLUSN]

ORP measures redox potential of water. basicly wether the water is in oxidative state or a reducing state litriture says keep it within 200-400mV. My tanks are VERY well maintained with fish spawning weekly so i assume the water quality is spot on (ammonia 0 nitrite 0 nitrate 10-20 (i add fertilizer) temp 28-29C ph 6.5).
orp meter is new $15 off ebay just dont know how to make it read correctly

[BT Gunner]

i think the time on the forum is wrong, its 7:22pm now but ILLUSN post says 7:48pm

[sharkbaitnemo]

try these guys for calibration fluid
http://www.milwaukeemeters.com/accessories.htm

[ILLUSN]

thanks mate, your a legand must have looked at that page a hundred imes and missed it. :banghead

[Bad Inferno]

Illusion,

How did your ORP measurement go..What was the value ?

[Proteus]

i think the time on the forum is wrong, its 7:22pm now but ILLUSN post says 7:48pm

You need to adjust your time in your profile to +10 hours. (the default time on the site when not logged in is correct).

An ORP meter for $15, sorry, but that is as good as buying ice cubes off someone on the main street of Cairns. :lol: :lol: :wink:

Considering an average ORP meter costs over $400 and a good one several thousand dollars I wouldnt put much faith in the results you get.

For a FW tank you want to keep your Redox level at between 250 & 325 approx, for SW between 275 and 375 and if you are using ozone for that to cut out when the value gets above 350 (some push it and go to 400).

A SW swimming pool should have a redox of approx 400 and a chlorinated pool at 600.

The cheap hand held units are more designed for swimming pool use and after a few uses get thrown away.

[Bad Inferno]

Proteus
IS a lower ORP value better ?

I've just stuck my probe into the tank and its reading 233 mv. and before you ask the ORP monitor is worth $1,500 and I did pickup an aquarium ORP sensor (Platinum wire) for ~100.00.

PS I did not have to pay $1,500 got it cheap :) however it is an industrial ORP/PH monitor. Has 4-20ma output so I'm about to place it inline with my canister and start trending the value over time.

[Bad Inferno]

My tap water is 270mv

[Proteus]

Has 4-20ma output

Sounds like one of the good ones (based on that range)

233 Eh/mV is fine, slightly higher would be better (250 - 320)

For those that are scratching there heads wondering what we are talking about...


Redox potential is a basic measure of the water's ability to cleanse itself. Regular aquarium care increases the redox (oxidation/reduction) level by keeping fresh toxic-free water in the aquarium environment.

In a long established, fully cycled aquarium, with the addition of an adequate UV sterilizer, a near perfect environment can be achieved for your fish. This does not mean you want pure water in the sense that it has been striped of all of its ions, minerals and compounds. Fish are not adapted to "perfectly clean water", such as distillated water, but to ecologically clean water with definite content of organic and inorganic compounds, micro-admixtures, ions and even bacteria or saprophyte. This is a result of good filtration, sterilization and a good water change regime based on water chemistry, not one that is based on day of the week, or because you feel it is required.

Something a lot of people dont know is the dramatic effect the Redox Potential level can have on algae. Higher ORP levels seem to be able to sustain Blue and Green algaes, whereas reducing the ORP level can change that algae to Red & Brown algaes which are more readily accepted by some fish species as a food source, as well as being easier to be eliminated in the filtration and sterilization process.

I have 3 ORP monitors running at the moment, and have used several other different brands in the past, and they can be a great tool in conjunction with a pH monitor in determining when to do a water change and the overall 'health' o your aquarium environment.

[Bad Inferno]

Well got the probe inline...did a call with 400 mv solution was wihtin +/- 20 mv which I thought was great for an orp reading. Its inline now and is reading about 120 mV :?

http://img.photobucket.com/albums/v319/rjconway/aquaprobes.jpg

I know this arrangement is not the best however the width of my cabinet requires this connection. Next tank will be slightly wider so I'll be able to take the outlet at a higher point so that air does not accumulate in the top part of the TEE's. The PH & ORP probes are well into the TEE piece however my conductivity probe is the one that would get the air pocket (its the middle one). If this happens it will instantly go to 0 anyhow, so I'll see how it goes.

[ILLUSN]

Hi bad inferno, got a new orp meter (threw the other one out wasn'y calibrateable) reading is between 240 (straight after water change and filter clean) to 345(just before water change and filter clean) stays at about 290-330 most of the time. hooking up a 24w uv sterilizer soon will let you know how the value changes.

[Bad Inferno]

Got it trending at 6:30 pm. Spikes in conductivity and ph are when I was fitting the orp sensor inline. I also did a water change 6:30-8 pm so you can see the temperature come up. I don't know if the ORP followed the temperature rise or it was stabilising. I'll leave it for a couple of days and do another W/C. I know my ammonia / Nitrite is =0 however my Nitrates are high >40 ppm. So I'll do a 40% water change and try and heat the water and see what the difference is in a couple of days. I did do a calibration check with 400 mV solution and it read ~415 mV before installation. Only thing I don't know if it reads the same if I just place it in the aquarium as apposed to my inline installation. I might also try and reduce the canister flow rate and see if theres a difference.

http://img.photobucket.com/albums/v319/rjconway/orp1.jpg

[Bad Inferno]

Illusion,

What is the time frame between your water changes ? if your reading changes 280 to 340. What % water change do you make ?

My reading stabilised at 160 mv then with a 15% W/C went down to 137 mV. So your mV goes down with a W/C as well so why is a higher ORP value better ?

[ILLUSN]

Hi Bad inferno, I change water twice a week, 40% every wednesday 50% every sunday. The lowest reading is just after a water change and a clean of the filter (aquis 2400) i clean the filter monthly, just before a filter clean the reading gets up to 345 i assume due to the build up of crap in the filter. tank is very heavily over stocked 340L with 8 discus (4-7inch) 2 giant plecos (over 18" each) 4 masive SAE's (5 inches) 8 rainbow fish (4 inches each) 2 yoyo loaches (4 inches each) 4 kullie loaches (2.5") 4 big bristlenoses (4-5") 4 dwarf loaches (2"), 20 cardinals (1.5" each). I'm not sure if a higher is better as mine gets higher when its due for a change.

[Bad Inferno]

OK been doing some more testing:

OK three tests today..
1. Tue 8:30 did a 30 litre water change, conductivity went down and so did ORP. I run out of kh buffer on the weekend so aged water is very soft, usually add a tablespoon to 100 litres.

2. Wed at midday Increase ph setpoint from 6.2 to 6.3 (ie less CO2 injection) No change to ORP

3. Wed 6 pm turned off UV for 1 hour , could see an effect after about 5 minutes. ORP went down quite fast in fact....turned it back on (7:00pm) and again up it went.


http://img.photobucket.com/albums/v319/rjconway/phincrease.jpg



Well I just about ran out of sera florena (plant fert) however did get probably< 5 ml out of the bottle. Had an immediate effect at 8:00 am in lowering the orp value and took a number of hours to recover.


http://img.photobucket.com/albums/v319/rjconway/orpfert.png

So at this stage everything I have done actually lowers the value....Still looking for the magic that increases the value. Maybe I'll just wait it out and see if it naturally goes up. When I installed the unit I did take the opportunity to clean the filter as well. I have also noticed at 2:00 pm each day the ORP went down slightly...nothing ever happens I thought at 2:00 pm however I now find out my wife feeds the fish at 2:00 pm which causes a slight ORP drop as well.