PH SWINGS

[blemmy]

I would be grateful for any comments/advice from forum members on the following.

Around a month ago, I diagnosed a parasite problem in my pond by microscopic scrape and the treatment I used was PP. unfortunately, whilst the PP did the trick with the parasites; it hit my filter quite hard and I had a subsequent nitrite problem. I added salt to 0.3% to counteract brown blood disease, (which I have maintained at this level for the last month - incidentally my nitrite level had dropped to zero again when tested yesterday evening and I will now commence water changing out the salt) and also added a filter booster (Micro-Lift Nite-Out II) as per directions and increased aeration significantly.

Whilst I did not have a blanket weed problem when starting the salt addition a month ago; initially I noticed quite a bit of what I would describe as slivers of green slime algae algae up to thumbnail size being caught up in my nexus and it looked like this had been dislodging in little bits off the fibreglassed sides and bottom of the pond. This ceased after about 2 weeks but then I started to notice strands of duckweed(?) getting caught in the nexus which was coming from one or two small clumps which were growing in isolation around the sides of the pond - I assume that the salt was killing it off?

Following a water change last night I tested my parameters at 9pm and they were:
Salinity 0.3% (Digital meter)
PH 8.0 (New Digital meter - used for first time that night after checking calibration)
Gh 6.0 (NTL Test Kit)
Kh between 4.0 and 5.0 (NTL Test Kit)
Nitrite Zero (Kusuri Test Kit)

I then tested my PH again this morning at 9am and it was 8.5.

I would be grateful if anyone could tell me if this fluctuation in PH is something to be expected under the circumstances and is my PH reading within acceptable parameters as the literature on the subject has me a little confused?

Any advice would be greatly appreciated.

Many thanks'

Paul

[Duncan]

hi paul

the swing you mention is normal however youfigures are an exact reverse of the swing you would expect

normallt pH is lower in the morning and higher at night thats normal events
is there any chance you have reported the swing wrong?
dunc

[blemmy]

Hi Duncan,

I have taken another PH reading tonight at 11.15pm and it was 8.0 - the same as at 9.15pm last night.

I will take another at around 11am in the morning and will post both readings then. The readings I posted earlier were the right way around and that's what got me flummoxed in that they seemed to be the wrong way around versus what you would expect, to me as well!!? Having said that I took the readings using a new digital PH reader for the first time (HM-90) and on checking the instructions I may not have followed them to the letter when taking the second (morning) reading I reported. I have followed them exactly tonight and as anticipated got the same reading as I did at 9.15pm last night, i.e. 8.0. Possibly I may not have cleaned the probe properly before taking the second reading this morning but have done so in readiness for tomorrow morning before taking a reading. I will also re-calibrate the meter before taking the reading in the morning as I have found out that these HM-90s can require re-calibration each day.

Will report back in the morning and thanks for your help.

Paul

[blemmy]

Hi Duncan,

Took another PH reading at 11.15am this morning and it was 7.8. which is more like what one would expect and a pleasingly small range difference from the reading of 8.0 at 11.15pm the previous night. Seems that I may well have not properly cleaned and prepared my new PH meter when taking yesterday morning's reading!

Thanks also for your guidance that a PH near 8.0 is nothing to be concerned about and I can confirm it is generally always around that figure when I do my mid evening water changes and parameter tests.

Thanks

Paul

[Duncan]

well done you solved your prob and reiterated what I said it should be lower on the morning than at night

the reason is algae by photo synthesis use co2 and produce O2 during the daylight thus raising the pH during the night they use O2 and produce CO2 which forms carbonic acid thus lowering the pH

that's the normal event so pH is high at night low in the morning but this should not be a wild swing

dunc

[blemmy]

Hi Duncan,

Thanks for your response - your comments/advice are always much appreciated.

Best regards

Paul