Backyard Aquaponics
A place to discuss aquaponics

Tony can ya fix up another tank temporary and put your fish in it and check to see if the pH rises in 24hrs time as it is doing in your pond? I reckon those goldies like it high

i think hes already running that test for me in his other thread

DRD, I am out of aquariums and fish tanks that I want to use. (no good putting 8 GF in a 5KL tank is it? Nevva catch the buggers again ) I revckon that they have had it hi for so long that they really miss it when I put the bore water in.

I have taken a suggestion to place some bore water in a bucket with an aerator. I will report on pH tomorrow.

This is interesting!
The bore water sample was put in a clean plastic bucket with a bubbler on 1/11 and the pH at that time was around 6.5

I measured the pH on 3/11, after 2 days of air bubbling, at 8.4

How is this possible?
Could this be due to mineral content of the water?
Should I stop aerating the water in this pond?

Update on the pond readings:
Date - - pH - - NH3 - - NO2 - NO3 - Temp
21/10 - 8.0 - - 0.25 - - 0 - - - 0 - - 19.4
22/10 - 8.4 - - 0.25 - - 0.5 - - 10 - NA
24/10 - 8.2 - - 1.0 - - - 2.0 ! - 40 - 20.5
25/10 - 8.4 - - 0 - - - - 1.0 - - 40 - N/A
26/10 - 8.4 - - 0 - - - - 0.5 - - 10 - N/A
27/10 - 8.6 - - 0 - - - - 0.5 - - 10 - N/A
28/10 - 100% water change No readings
29/10 - 8.4 - - 0 - - - - 0 - - - 0 - - 16°C
30/10 - 8.4 - - 0.25 - - 0.5 - - N/A - N/A Broken test tube - #*!!!#*
01/11 - 8.0 - - 0.25 - - 0.5 - - N/A - N/A

03/11 - 8.4 - - 0.25 - - 1.0 - - 20 - N/A
04/11 - 8.0 - - 0.25 - - 0.5 - - N/A - 20.5
The pH still sits near the top of the High pH range, I will dilute some to see what it reads. If I dilute 2.5mL pf pond water with 2.5mL bore water at pH 6.5, what correction should be used to give the pH of the pond water?

Jezz, that's interesting Tony....

Re the dilution, I'd suspect that you're in fact doing a 50% dilution so all things being equal the pH should split the difference from 8.0 & 6.5 =>7.2

50% pH 8.0 and 50% pH 6.5 doesn't make pH 7.2.

Unless you know how much buffers there are in the water, you can't really calculate pH back after diluting.

Probably correct Thomas.... was just a stab in the dark based on a gut feeling.... purely [s]un[/s]scientific [s]reasoning[/s] guesstimate

Tony

After aeration do you get the brown residue falling to the bottom of the bucket?

Tony, i reckon i might be on the mark with the bore water having a huge dissolved CO2 content. It would explain the positive PH drift apon airation.

The brown sediment that is dropping to the bottom is most probably iron oxide. I hear that WA bore water canbe very high in oxygen. I cant remember the exact formulas, but at low PH iron exists in a water soluble oxide form, as the ph increases it is changes to just your standard iron oxide rust which is not water soluble and hence precipitates out.

One of the reasons we use chelated iron for Ph's above about 6ish

I'd say you might get the same result from bubling air for only a few hours

This might be helpful, it would seem that total acidity (a term that i had not hear of before) may be due to both dissolved co2 and iron/sulphate compounds. The iron compounds drop out of solution at ph's above 6.5 possibly due to CO2 off gassing and raising ph. This then further raises ph.



see below. i have linked to the pdf at the bottom, just page down through it and look for the highlighted terms.

It is important to note that this equation only provides an estimate of acidity that is generally
applicable in areas with acid sulfate soils. In some areas, other chemical species such as
organic acids and dissolved carbon dioxide may be a significant component of acidity. If
groundwater is being pumped from a great depth or from beneath a confining unit, it may
contain high concentrations of dissolved carbon dioxide which is rapidly released from the
water on exposure to air. The carbon dioxide component of acidity can be determined by
measuring the acidity of water in the field using a proprietary test-kit, and subtracting the
calculated acidity value. More accurate acidity assessments can be made if redox sensitive
metal such as iron are speciated in chemical analysis.
Acidic water is generally defined as water with a pH of less than 6 where the Total
Acidity exceeds the Total Alkalinity of the water

http://72.14.253.104/search?q=cache:L8R ... cd=8&gl=au

There is no sediment in the bucket (a white 2 L cream bucket) from the aerated water. The sprinklers have a white residue on them from evaporated bore water, if that helps. I do not believe that it is lime, as the pH is so low, compared to water from the coastal plains which is around 8 - 12 and full of lime from the limestone in the subsoils.

I am not planning on performing any more water testing, I will just watch the Goldfish, feed them and check on the plant growth and algae blooms. If the algae gets to be too much, I will do a water change.
If the water temperature gets above 26°C, I will add some Tilapia to eat the algae.

Thanks to everyone for the support and suggestions. The Goldies are happy, the plants are happy, I will "Live and Let Live"

Tony

no worries tony. I'd now say that you have a reasonable water hardness ad the ph change is simply due to the water having a very high CO2 level straight out of the ground which then gases off.

same sort of thing that happens between day and night with thick algae.........

Tony

It is really wierd that you don't get iron in the water. How far did you go down with the bore?

The bore is a pre-existing one at purchase, so I don't have a clue how deep it is. Bores on the coastal plain frequently have iron compounds present, evidenced by the brown stains on the fences and walls, where the water hits. We don't get this up here in the hills.

I went down 80' and we get it this side of the hills