Backyard Aquaponics
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So today I received my pH/temp pen and after checking calibration I tested and found it to be 8.0 @ 23.8C so there is a big gap of what the api test kit is showing and I’m a little pi$$ed. The kit is new and in test dates and so is the calibration fluids but I’m annoyed in the void of the results as even a blind man could read the test tube results correctly so I wonder how close are the other results. I’m going to base my pH with the pen and continue wither the api kit for the other 3 tests. Does anyone else have these issues or come across this inaccuracy before? Obviously with a correct but higher pH reading it’s more important to have next to zero ammonia so am concerned about the true accuracy of my test readings. Following what the instructions say etc I have little confidence in reading it right thus stuffing it all up.
Sorry rant over.

Hey Liney,

I wouldn't over think it too much. At the end of the day you want to mess with the water chemistry as little as possible. I would just keep an eye on the readings and see where it lands. As long as your plants are ticking over it will all be good.

Regarding pH meters, I wouldn't imediately think the kit is wrong vs the probe. I currently don't trust mine either as I have not tried it in a calibration solution. I can get this from work, otherwise you can make standards. However, as long as my pH is above 6 and below 8-9 I'm not too fussed. I figure it will be a year or so before I see what the trends are.

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I’m going to base my pH with the pen and continue wither the api kit for the other 3 tests. Does anyone else have these issues or come across this inaccuracy before? Obviously with a correct but higher pH reading it’s more important to have next to zero ammonia so am concerned about the true accuracy of my test readings

Hate to say it but those pens are not the best at times and pH is a bit of a moving target unless you are clearly high or low pH. Had lots of issues with people using them in agriculture and landcare etc.
pH can be a bit fickle particularly when close to neutral (7.4-7.6) if it has no buffer.

Do you have any standard solution - particularly around 7.8 ? Be best to double check the pen.
Also note that the API test kits have problems when you test close to 7.4-7.6.
If you get blue (as per your previous slide) you need to double check with the alkaline pH test as there is overlap in the values. I see you realised this but at mid 7's you have to do both pH tests.
(see Petes threads about his issues)


+1 to Dr Fish. Don't mess with the chemistry too much because it is a hard one to keep stable over the long term.

Perth is very specific.
North of river is groundwater dominated and thus tends to be high pH and often a lot of buffer so hard to pH get down.
South of River is surface water and desal, and tends to yield low pH systems (my issue - south perth area).
They buffer the desal water back to mid 7's with calcite but in an AP it goes acidic pretty easy, particularly in winter.
Suburbs around the river vary depending on where they connect to the main supply.

Which API pH test are you using, the high or low range test? I'm not sure it will help but maybe there is a way to use the other solution just to see which is messed up (it might be the pH pen not the kit as mentioned earlier).

Thanks again gentlemen I would’ve thought a new pen calibrated with the correct pH solution would be accurate or how would they sell them? It’s showing pH 8.0 which is fine by me as it’s what has been mentioned our area usually is just want the other element readings to be accurate as it will affect my fish. My plants are going great and have noticed a little yellowing of my parsley which I might spray with a little seasol but that’s probably due to whatever pH it normally likes compared with what I’m providing.

If it's yellowing on the new leaves it could be an iron deficiency. I'm not sure what type of iron you're using but many types of iron are locked out at higher pH's. Iron EDDHA should work at this high pH or you can spray apply many kinds of iron directly onto the plant and you avoid the pH lockout in the system water.

Did your pH meter come with a calibration solution? Even then these need to be relatively fresh, especially the neutral range. I'm sure the dip probe is close, I think mine was out of the box, but I'm a bit pedantic and want to check it's calibration. There are some DIY calibration solutions you can make from things like baking powder/soda. I was going to try making some and testing it using our good system at work.

Yes, iron deficiency! Adding a little chelated iron is awesome, but yes get the right one for the pH range.

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Yes I brought a new bottle of pH 7 solution and probe cleaner etc so should be good there. Need to get some iron chelate this week from somewhere I didn’t see it at my local bunnings.


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Ok, well, if your calibration solution is fairly fresh then it should be giving a reasonable reading.

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I am NOR and my pH is low.
I have to use potassium bicarb to get it above 6.0.

So after testing for 4 weeks yesterdays ammonia and the day previous was 0 and nitrite 0 Nitrate 40+ Ive come home from work today and found ammonia @ .25ish nitrite 0 and nitrate 10 so all thats changed in last few days is rainfall so question to you knowledgeable people is would the rainfall contribute to this? Water temps are around 16-18C each test and pH is 8.0 and I haven't added any ammonia for a week. My plants are thriving and just the storm smashing a few chards flat appear to be my only casualties and was looking at getting 10 trout tomorrow as its my only chance for a while. Looking at the safe levels for TAN chart Id prefer to lower the pH to around 7.6-7.8 but each time I add the solution to drop the pH it rises back to 8.0 the next day so Im a little pi$$ed.
Suggestions please.

Cheers

the pH issue is pretty typical - it means there is lots of buffer (usually calcium based).
The rainwater might help if you get quite a bit of it, though it does tend to dilute rather than modify.
You will find a few NOR around who spend ages trying to deal with the pH and eventually just stay with it.

it is not unusual for system values to shift in rain like we have had.
The rainfall will flush the grow beds and mobilise some nutrients that may not be affected by the normal cycle.


If you want to know what level of acid is needed - what you need is a bucket of water and hydrochloric acid.
Keep adding the acid and resting 12-24 hours until it finally gets down to around pH 7.0
that will indicate how much buffering there is and how much you need to deal with it.

So this morning my ammonia is at 0 as were the nitrites so I got 5 trout and will get another 10 this weekend all going well. Nice to have something to eat the caterpillars as my frogs are a little lazy but the trout smash them. Made up a vacuum to clean bottom of fish tank so I can see if any food is left. It did the job but I’ll make a better one.


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Cool,how did you make a vacuum?

Well I’ve made a couple of rough designs from YouTube- the first was a 1M piece of 20mm pipe connected to a 500mm piece of 20mm hose joined into a 50mm pipe fitting into the SLO outlet that worked ok but the pipe was too stiff and if I’d had flexible hose would’ve done well so will get some this weekend and try again. The other version was same pipe into a backup pump with hose coming from top of pump into a bucket- bloody hard and a few laughs from the wife.


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