Its a meter i got it off ebay heres a link to the one i got PH METER , FOR ,MARINE AQUARIUM, FISH POND,HYDROPONICS on eBay, also Filtration Heating, Fish, Pet Supplies, Home Garden (end time 30-Oct-08 14:48:01 GMT)

I'll let you know the results in 2-3 days when i next water them.
Is that the only thing it could be ph?

Cheers
Tom