# Odd PH readings?



## Rob P (1 Dec 2013)

Bit of a major change around yesterday. 

Swapped existing 800lph filter for Tetratec EX1200. Also took co2 off inlet and fitted up style atomiser on outlet. 

Did some PH readings throughout the day and they looked good. PH dropped to 6.4 and held pretty consistently all day.  Didn't actually test before Co2 on but had some old tank water left in a bucket and read 7.5.

Dipped my ph pen in this morning before 50% water change and ph still 6.7!? After water change now 7.1.

Why had my ph not climbed back up to 7.something over night,  co2 off since 7.15pm? 

Thanks, 
Rob


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## darren636 (1 Dec 2013)

Test again just before gas on


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## foxfish (1 Dec 2013)

Test your tap water!


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## Rob P (1 Dec 2013)

Tap is 7.3 (just done it). Tank before lights on 6.6.

Unfortunately wasn't here when co2 switched on, got home about 40 minutes after and it was 6.8.


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## sa80mark (1 Dec 2013)

Have you tested tap water after gassing off ? Left for 12 hours or better still 24 hours,

I did mine last week and it goes from approx 6.4 out of tap to 7.9 after 24 hours


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## foxfish (1 Dec 2013)

Exactly .. your tap water will contain Co2 so after a water change you can expect a lower PH reading & your pre-set reg will lower the PH even more during water change day.


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## Rob P (1 Dec 2013)

Guys, yes I've done the straight from tap and left 24hrs/48hrs and is always around 7.5 +/- 0.1.

Every time I've set out to do a PH profile I've tested tank water in the morning and read 7.3/7.4. CO2 is on around 12.45pm, lights 3'ish. 

I've been improving flow distribution and co2 for a while now which has meant small adjustments to injection and on/off times. 

The low PH reading of 6.7 this morning was when I would normally read it at 7.3. The reading of 7.1 was after the 50% change which I'd expect after putting 50 litres of ph 7.5 water into a tank reading 6.7.

I'm not overly concerned, the fish etc seem happy and active. But it's always nice to know why these things happen


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## Rob P (1 Dec 2013)

Mystery solved, just gone to double check on/off times on time clock and my stupid sausage fingers must have pressed some segments on the timer when swapping everything around yesterday, so co2 came on last night/this morning from about 4am to half past 5! That'll explain the depressed PH early morning lol


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## John S (1 Dec 2013)

Sounds like a lucky escape.


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## Rob P (1 Dec 2013)

Yup, I'm just going to double check again... lol


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