CWP 24-7 meter Inaccurate during lights-on

I'm getting clones on Friday for my first grow, so I've been test running everything to work out the kinks before I have 4 little green-lady lives to be responsible for. Tonight I found something interesting.

So I PH'd and put nutrients in my water, got it to the right levels I was shooting for, write down my numbers to study later, great... Then I turn the 1000w light on in the room, and my PPM shot from 300 to 3000, and my temp reading went from 60 to 120!

At first I thought it was just that the meter was too close to the ballast, then I thought it was the fact that it was powered on the same circuit as the light... Well I tried powering it on a different circuit, and held the display as far as the leads would let me get out of my closet - about 2 feet out. My PPM is still reading 800 (is 300 when lights are off) and the temp shows 70 (60 with lights off).

Any suggestions? I don't really want to recalibrate to when the light is on, as then i HAVE to do everything while the light is on, and the amount it's off fluctuates, so it would be inaccurate.

Thanks ya'll!

Get your meter off that circuit, or it could get damaged beyond repair. Ballasts, whether Magnetic or Digital are " dirty" electrical devices. They throw off all kinds of voltage spikes/dips and harmonic imbalances on the circuits they are fed from. Lighting should be kept on its own circuit if at all possible. The older the ballast, the "dirtier" it is to the circuit that feeds it. On a side note, try not to plug any power tools ( drills, saws ) into the circuit that feeds your meters, if you have to, unplug the meters till the work is complete.

Hope this helps M8. Good Luck

Peace

Asmallvoice

Sorry M8, I am fighting a serious chest cold, and the meds are keeping me a bit woosy. I reread your post and seen that you already tried it on a different circuit. I sincerely hope the damage has not been done to your meter. If it will not stay relatively constant on a different circuit there are only 2 possibilities that I see ( 1 the damage has already been done to your meter ( hope not) 2 the ballast for your light could be faulty ( doubtful, but still a possibility ).

Hope this helps M8. Good Luck

Peace

Asmallvoice[/QUOTE]

Hey I know u spent money on a meter already but the Myron company makes these meters called the ph pen. While it does not measure ppm/ec, there is another pen that does that. Also for the same price as you would pay for a 3 in 1 meter. I've found these to be extremely accurate and reliable. My plants have never been happier. The price of good meters can get costly these pens are nicely priced and a very good product in fact once I bought the pair ec and ph pens and found them to work well everyone at the grow shop i work at has made a change to the pens as well.

The reason I want to use a constant meter with leads always in, as opposed to hand held ones, is the location of my res. It's in a stupidly hard place to get to, as I'm working in a really small closet space. I'd like to be able to monitor everything without moving the pots, pulling up the board, pulling out the res, and testing by hand.

I did a little more testing, and it's definitely the ballast that is interfering. Strange tho, it's a brand new dim-able ballast! So even with the meter plugged into a different circuit, my PPM is off by 500, and my temp is off by 10 degrees. Well I put the dimmer down to 75%, and I was off by 400/8, 50% 300/6, 25% 200/4 (approximate numbers) - and with the light off completely, I was spot on again.

Has anybody had this problem, and found a way around it?! I might think about trying to shield the leads and see if that has something to do with it. Fingers crossed!

Sent off an email to CWP, but I'd still like to hear anybody else's suggestions if they have any!

Here is their reply...

What you are describing is classic EMF discharge coming from your ballast. EMF (Electrical Magnetic Frequency) pollution has become a problem in the indoor gardening industry. 99% of the complaints come from digital lighting ballasts that do not meet FCC rules of electronic frequency pollution. If your 24-7 meter is being affected you can be assured that other equipment in your home and your neighbors homes are being affected. Should your ballast be affecting the neighborhood's electronic grid, you will get a visit from one or more companies supplying entertainment services or your power company. You will responsible for the effects to your neighbors TV's, etc. and fines (check the fine print in your power and cable companies contracts). These visits do happen as previous emails from our customers have shown. You are not alone in this problem.

Not all electronic ballast manufactures have this problem. It stems from electronic feedback sent as a broadcast signal from you ballast, much like a radio station broadcasting. Since you have tried all of your circuits, one must assume the meter is picking up a powerful broadcast signal coming from the ballast, usually from the high voltage DC lamp cord going to the bulb. This DC cord is the broadcast antennae.

We can't design the meters to operate around ill designed electrical equipment without the use of lead shielding. This lead shielding would keep the meters from performing their given tasks. We would have to supply enough lead shielding to wrap your hydro system tank because it too is receiving the EMF broadcast.

It is not our equipment that is failing you, it is the digital ballast. Regular coil wound ballasts do not give off an EMF that effect other electronic equipment.

I hope this helps you.

Thank you for purchasing CWP Instruments.

Let me know your thoughts.

CWP Customer Support

Looks like I'll be throwing down an extra $50 for a digital ballast compatible meter, like the Hanna one. Wish I had known this from the start! Oh well, live and learn!

http://www.amazon.com/Hanna-Instruments-Temperature-Monitor-Displays/dp/B002ZG8L7G/ref=lh_ni_t