Need to calibrate?

[walton321]

Hi: I bought a TDS meter from ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=294&item=194315661 7&rd=1

I'd like to know if I need to calibrate it as I didn't buy any calibration solution. When I put it in tap water, it reads 50 ppm. When I put it in DI water it reads 0. Also what should be the optimal ppm for breeding water?

Attached is the picture of it.

Thanks
Walton

[daninthesand]

Walton.

I am not familiar with that particular meter, but it looks like a Hanna. If I can make out the writing in the picture. The ebay auction states that the meter has a one point calibration. If the ebay ad. is assumed to be accurate then it is likely this meter has been calibrated. It says so in the add. My experience working in a lab makes me confortable saying this: an uncalibrated measurment device of any kind is not useful at best. Dangerous at worse.

If you assume the ad. on ebay is not honest then the meter has not been caibrated. ???

Without calibration, the tester cannot be assumed to be reading accurately. If it read zero in DI water, there's no way to know that it is reading correctly. If you know for a fact that your tap water is 50 by another accurate meter, then it is safe to say that your meter is perhaps close.

I'd suggest you get the calibration solution designed for this specific meter. Check out the website for this brand and obtain the calibration solution.

Until you get the cal. solution you can get an idea if the meter is at least close if you have access to someone who has a properly functioning meter. A friend perhaps, or a hydroponics store, or a place that sells RO units. Get them to compare the reading you measure with yours against a calibrated meter in a solution of known concentration.

You could see if they carry the proper calibration solution there as well.

HTH

Daniel

[dm]

I also got mine today. (thanks randall).
What I want to know is what is a good range of TDS to have?

[Ardan]

Hi,
You have to experiment to see what works best for your particular fish. Use the meter to measure and repeat conditions.

However, general guidelines are about 100 ms which is pretty near equivalent to 70 on a tds meter. This is suppose to result in good hatch rates (soft water), but people have had good results in water 2 and 3 times that hardness

hth
Ardan

[dm]

Mine is reading in ppm. It is showing a little over 300. That is with 2/3 RO. I'm not breeding now but hopefully this will give me a real good indication of how much to cut the RO water if and when I do breed them if I can get it figured out.

[Ardan]

What is your tap water reading?

If it is 300 ppm with 2/3 RO, then the tap water must be very high??

Ardan

[dm]

Tapwater = 547
Tank Water = 300
RO water = 50

[Ardan]

Hi,
The RO water seems a bit high. Usually 25ppm or less is from an RO. However, you will probably need to use 80% RO to achieve around 70 ppm water. Maybe try a bit higher for starters or you will use a lot of RO water.

Shoot for 100 to 150 ppm water for starters?? SOme have had good success in that area.

hth
Ardan

[dm]

Thanks for all the help.

[tjudy]

:)
The meter pictured is a Hanna meter, but an older one. That model is not offered in their current distributer's catalog. The instructions with the meter should indicate what the calibration procedure is. If you need solutions please let me know..

mesquito_ted@yahoo.com

[walton321]

Thanks for your replies. I guess if other people's tapwater reads 300ppm and mine is 50. I don't think I am that lucky to have free soft tapwater. I'm in Staten Island which is at the end of NYC's water supply system so I'm sure the water picked up plenty of minerals along the system. I better order some calibrating solution.

Walton

[cgrim10]

that is the same tds meter i got a year ago. i took mine to the culligan place and checked it against their high dollar meter, and it was within 5ppm tds. still shows tap at 450/475, and r.o. at 12/17 ppm tds. after a year and still works fine. it suprised me what salt does to your tds. i wouldn't have realized it any other way. cg

[RandalB]

Dale,
50 PPM from a RO unit is not unusual given the TDS in your feed water. You could almost use straight RO in your tanks. The best ways to lower it would be to increase feed water pressure or use a DI unit.

Hope that TDS meter is working out for you...


Regards,
RandalB

[RandalB]

OH BTW,
I also have that meter that is pictured above. It is a Hanna Instruments, Manual calibrating model with a 0-999 PPM reading. Mine was within 5PPM of accurate out of the box. (Also bought it off E-Bay) I think Hanna calibrates them before shipping as My new Primo meter was dead on.

RandalB