White Patches on driftwood and tank glass

[plantgeek]

Hi all,
I've got white patches on driftwood and tank glass after I've done 20% water change. The water has been aged for a day as well as treated with anti-chorine. I've tested the water and the PH is 7.0, Chorine is zero. What could be the cause? Two of my cherry shrimps died last night after the water change. Previous water changes have resulted only in the white patches. Any help or advice would be helpful.
Thanks!

[puffer07]

maybe you should try to lower your PH. How old is your tank ?

[|squee|]

Pictures of the white patches will help. Clear detailed pictures.

[plantgeek]

Hi all,
I could try that first.. the PH value is 6.5 - 7.0 after water change.
I'll try to get some pics after the water change this weekend.
Thanks all

Oh yes.. forgot.. the tank has been running for 6 mths...
sadly just died another 2 cherry shrimps...

[XnSdVd]

Do you have any large snails in your tank? If those "patches" are a few mm across they're probably snail eggs

[plantgeek]

Nope no snails at all... I think they're calcium or lime deposits from the water we're using here... but why onli at water change time I have no idea...