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View Full Version : pH probe goes nuts when UV sterilizer is on!!!!

geshields
02/20/2005, 02:18 AM
I have a dilemma.

I have a pinpoint pH monitor and when my Aquaultraviolet 120W is turned on, my monitor goes nuts....4.25, 6.7, 5.4...never close to normal..and never stays on one number...

I have tried the monitor on AC power..and also with just the battery installed. I tried switching probes. Tried switching monitors...etc..it still goes nuts..UNTIL I unplug my UV then bam!! 8.1, etc..rock solid...

ANY IDEAS????

Greg
jdg
02/20/2005, 02:31 AM
How far is your UV from the monitor? I've seen it happen with their SG monitors but never with their pH monitors. I was going to suggest to plug the two into different circuits, but since you tried the monitor on DC power only with AC disconnected that's not likely. It sounds like your UV is spitting out some sort of EMI ... what kind of UV is it?
geshields
02/20/2005, 02:38 AM
Model is here....made by Aqua Ultraviolet...

http://www.marinedepot.com/md_viewItem.asp?idproduct=AV2391

UV is right after the return pump...monitor and probe are in sump...prior to the return pump..but opposite side of the sump...about 45" away...

I also thought electrical interference...until I tried it with the 9V battery only...with ac unplugged...

Also, UV is new...pH monitors are about 1 year old with 3-6 month old probes..calibrated 2 months ago...

Greg
jdg
02/20/2005, 03:00 AM
Wow ... that's a big UV unit ... I hope it's for the 450 and not the 62. :D

It seems like you're UV is putting out some sort of EMI ... could be the powersupply, could be the bulb. Is it possible to shield the power supply for it in aluminum foil for a test? The unit itself is probably too big to shield. :(
Habib
02/20/2005, 04:42 AM
Sounds like an electrical interference.

Using another power outlet or using batteries for the PP monitor might help.
geshields
02/20/2005, 10:17 AM
Originally posted by Habib
Using another power outlet or using batteries for the PP monitor might help.

I tried with batteries only and still the same thing....

How would EMI interference be transmitted through the water..??

Greg
jdg
02/20/2005, 12:51 PM
Originally posted by geshields
I tried with batteries only and still the same thing....

How would EMI interference be transmitted through the water..??

Greg

Not through the water, through the air ... and perhaps even amplified by your reflectors ...
FinsReef
02/20/2005, 12:54 PM
Check the voltage in your tank, I suspect that your UV is leaking voltage in the tank.
jdg
02/20/2005, 01:24 PM
Originally posted by FinsReef
Check the voltage in your tank, I suspect that your UV is leaking voltage in the tank.

Good call ... grounding probe should take care of that though, no?
FinsReef
02/20/2005, 01:36 PM
If it in leaking enough voltage to make your PH probe to go wacko, basically you have a faulty UV, and should not use it. A ground probe does not not stop the UV from producing the voltage, it just gives a plane to ground. If it is leaking, for your fish and you, get it sent in for repair by the company.
jdg
02/20/2005, 01:43 PM
A voltmeter should be able to verify ... never even thought about that ... :D