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Hawkey
12/03/2006, 09:39 AM
Quick question guys, every saturday I do my 5 gallon water change (with Reefers Best Premium)

I heat the water to around 28c then mix salt to correct level 1.025, then add my calcium. Leave mixing over mix. Then turn off return pump in tank, gravel clean and sypon water out (5gallon), then add new water into sump and switch back on return pump.

I have recently installed a ph probe (aquatronica) 2 weeks ago, and both time I have done a water change i have seen the ph jump, last week went from 8.40 to 8.60, during the week it gradually dropped to 8.40 by friday. Then did water change today and it jumped to 8.82!

Can anyone explain this?
thanks
Paul.

Mad Mitch
12/03/2006, 10:33 AM
Personally, I use LR, miracle mud and sand bed so not into frequent water changes, esp weekly.

A few questions come to mind:
Source of water?
Have you tested ph?
Have you calibrated probe?

Reards

Mark

Hawkey
12/03/2006, 10:40 AM
Comes from my RO unit which is about 6months old. Maybe worth testing the ph of that.

Yes i recalibrated probe now at 8.73.

I have tested tank water with a kit though. That might be worth a try in case probe is out.

Mad Mitch
12/03/2006, 10:51 AM
Yes,

worth testing, and, forgive me for asking but, have you changed the cartridges in your RO unit - some suppliers do not highlight need :-(

Regards

Mark

Hawkey
12/03/2006, 10:57 AM
Well would you believe it, test kit reads 8.4!

I could only calibrate with 10 and 4, ideally i would have got 7 instead of the 4.

Would this make much difference?

Mad Mitch
12/03/2006, 11:05 AM
Lets start from first priciples. The reason for two calibration points is to define the range not just the mid point.

Whch test kit reads 8.4? - you need to calibrate sensor at 10 and 4 - then voila ... n.b. sachets are not intended for re-use if you do, use them for recalibrating between the reocommended intervals.

Regards

Mark

Hawkey
12/03/2006, 11:18 AM
Tropic marine. tested at 8.4

I used 10 & 4. But i would have thought it would have been better to narrow this to 7.

No i never re-use calibration fluid.
Paul.

Mad Mitch
12/03/2006, 11:38 AM
Paul

OK. The purpose of two solutions is to define / reprogram the range as well as the mid point for the probe/sensor

Presumably, all in the tank still looks well.

I have been waiting ages for the distributor to provide redox calib soln - meanwhile, I am more concerned with the chart profile than absolute value, and of course, observation of the captive residents :-)

Regards

Mark

Hawkey
12/03/2006, 12:20 PM
Yeah all looks absolutely fine. just wondered why i seem to get this spike when i do a water change. I might test the ph of the new water next time. Last week it took about 5days for the ph to drop from 8.6 back to 8.4

However, all the corals have their polyps out and seem absolutely fine.

Cheers
Paul.

RobbyG
12/03/2006, 06:08 PM
By any chance are you cleaning the probe with RO water?

Hawkey
12/04/2006, 01:14 AM
Hi Robby, the probe is only 2 weeks old in the tank, so i haven't cleaned it yet. I dip and dry in RO water in between calibration.

RobbyG
12/04/2006, 12:33 PM
Hawkey dont put it in RO water, it will shorten the probes life, just dip it in regular Tap water.

Hawkey
12/04/2006, 01:21 PM
I put it in RO twice when i 1st got it and then when i re calibrated last weekend. But ok no problem, I'll make sure i don't

Out of interest why does it shortern the life?

Will it have damaged it the probe the 2 times i put it in RO?

PH is now back to normal 8.4 all day, dropping to 8.2 at night.
thanks
Paul.

RobbyG
12/04/2006, 03:42 PM
Good Question, I have no Answer !! LOL I have just read that on the forum over and over, "Dont clean pH probe with RO water".
Here is a good link about cleaning the probe. As you will notice they use Tap water, also Pinpoint recommends Tap Water.

http://www.reefcentral.com/forums/showthread.php?threadid=927056&highlight=best+way+to+clean+a+ph+probe

My first probe had less than a 1 year life and I think it had to do with the fact that I cleaned it with Ro for the first 6 months. In the end it just never kept a consistent reading. Your two cleaninngs would not be a problem I think!

If you find out why RO is bad please let me know, I bet it has to do with the RO leeching out the chemical inside the Glass tube.

Hawkey
12/04/2006, 03:54 PM
Cheers Robby. Will keep you posted if i find out! Paul