Backyard Aquaponics
A place to discuss aquaponics

Ok here goes, with a sump tank and fish tank where would you recommend taking your water from to be tested? From the fish tank where ammonia levels are important or from the sump tank where nitrate levels are important, not to mention the KH/GH levels,

For the record my PH is 7 and KH is 4. GH is 8,

Test from both and see if there is a difference an if there isn't then take it from wherever is easier. If there is a difference I'd personally pay more attention to the FT given that's where the fish are and you'd assume the water they are swimming in would affect them more should there be a problem with it.

In my system the levels are pretty uniform all around the system. I haven't noticed any differences from one point in the system to another. I prefer taking my readings from the water going from FT to GB as this is what ultimately affects the growth of the plants, which in my opinion should be the goal for an aquaponics system.

Cheers for that but if my KH is 4atm I shouldn’t have to much of a swing between the two, but you are right about the fish being important, although there only gold fish atm. System is new, what about the marron? In the sump tank, they look delicious atm and feeding well,

Thanks for reply kij2, but I have a sump tank that supplies water to the fish tank and grow beds, the water from the grow beds filters back into the sump tank and the fish tank water gets filtered of fish waste that then goes back into my sump tank,

that’s why the question was up, as everything is pumped out off the sump tank but the fish will still need checking,

I am new to this too, but I value your answer, as shared knowledge is the best kind of knowledge!

Cheers mate,

pH is logarithmic and changes are slow, therefore measurements are unreliable within a 12 hour period. Having said this, there shouldn't be any conflicting tests at any part of the system.

Water returning from my GBs to the FT is typically pH 0.03 to 0.15 lower than what is in my FT when the fish are eating enough or other NH3 has been added, due to all the Nitrification going on in the GBs. It does vary somewhat during the pumping cycle though, greater near the start than at the end, by which time the water is mixed to a greater degree.

I'd expect different readings straight from the GB, especially if on a flood and drain. Although, it's still unreliable as a reading and gives no useable information.

Charlie, the woman on you tube said that a high PH would be better for establishing the bacteria for the grow beds, plus the fish don’t mind a higher PH, I test every few days atm at different times of the day so as not to get the same results like you would at the same time everyday, so what do you recommend? My PH has come down a bit today but it was high on Saturday? Around an 8, as I said in other post I have seashells in my bio filter to increase PH to attract the bacteria so the cycle can start before I add my Barra,

Any advice would help

I'm not sure why you think that Charlie. If it is consistent, then I know things are running well. I can tell how well mixed an addition of KOH or Ca(OH)2 is by the variation between ST (where I add it), GB return, and FT.
However, if I saw that the returning water was significantly higher pH after I'd disturbed the media in the GB, I reckon it would indicate I'd probably disturbed an anaerobic zone, and I should keep a close eye on it, or perhaps somone had dropped a shovel full of Hydrated Lime in!
Once you know how the readings behave under normal operations and activity, variations on this can give a good indication that something unusual is going on.

Consistency, with any variations understood through observations over time is good, deviations from that behaviour indicate further investigation may be required.

Blizz, a higher PH during cycling is preferred so is higher temps but your months off introducing the barra so I wouldn't let that fuss you too much at this stage.

Gunna I hear your view, my angle is any sulphurs and acids released from the beds are only minimal but because they have had time to drop PH during retention time this is a little unreliable as when that volume is diluted through the water body it levels out to overall system pH.

My system works in the exact same way your system does, FT to GB to ST and back to FT. However, I is important to note that filtration in your GB(s) usually takes a long time, much slower the the speed of the water circulating through the GB(s). This means that water coming in, leaves the GB(s) relatively unchanged in each cycle. This is true at least in my system. So basically the pHs and other parameters should be relatively uniform throughout, with small changes that are not usually registered in a typical API kit.

Having said this, I would like to point out that my experience with this comes from my own system, and any modest research online I have done on my own relating to aquaponics.

good quest Blizzard... ok in your sump see its feed via your GB... this is the point your max amount of nitrification has occurred therefore implies at this point your pH will be at its lowest. I'll usually sample here for pH and buffer occuringly.. in your FT I'll test for ammonia and nitrite seeing these are harmful to your fishes in high amounts so I'll test here and dump out water or dose with salt occuringly.. you can sample in sump for amm and nitrites to see the changes in FT to sump reading to see how effective your conversion of nutrients is and base on this you can calculate your max amm conversion per pass and even per day... cheer its all in the maths.

Cheers cookie! For the advice, I shall do the tests in future due to your recommendations,

no I'm here to help in anyway I can