conductivity?

[JasonC]

So based on the number of discussions on the accuracy of conductivity rather than pH in a low pH tank, I purchased an inexpensive conductivity meter and recieved it today and started checking water. I got some odd results that I was hoping you all could help with:

- plain tap sits at 230ish microsiemens, and 7.4 - 7.8pH
- tap trickled through peat and aged is 210ish microsiemens, and solidly 6.0 or below pH (only have drops to test pH)
- tank water that is appx 1/3 peat filtered, 2/3 tap is around 210-215 microsiemens
- tank water that is all peat filtered, appx 50% PWC's every few days is over *500 microsiemens*!!
- tap filtered through carbon fridge filter 210 microsiemens

So what is the deal? I would have thought the peat filtered tap would have been much lower in ms than the tap... according to my meter, it still falls within what it considers "hard water"? I certainly would not have expected it to be more than double the tap water value once it had aged in one of my tanks!

So what am I missing here? Is my peat filtration process not nearly as efficient as I thought it was? What could be affecting the tank with the over 500 microsiemens water? What is the ideal range of microsiemens for most apistos?

thanks!

 

[regani]

there are other ions as well that are contributing to conductivity apart from calcium and magnesium (which are responsible for water hardness). common salt (sodium chloride) for instance but also any of the additives to adjust pH. decomposing organic matter in your tank as well as added fish food will also raise the conductivity over time.

there are two possible reasons why your peat filtration does not lower the conductivity more. the contact time with the peat may not have been long enough or not enough peat to remove most of the Ca/Mg; or there are other salts present in your water that are not affected by peat. what is the actual GH before and after peat treatment?

if the conductivity goes up in your tank it means there is something in the tank affecting it. this could be decorations or substrate leaching ions onto the water, (e.g. shell grit, aragonite or similar) or maybe it comes from 'salty' foods (e.g. brine shrimp not properly rinsed).

I am not sure about the 'ideal' conductivity for apistos, it would certainly depend on species. I keep mine in either ~120uS or ~250uS water and they seem to do fine and breed as well.

 

[dw1305]

Hi all,

tank water that is all peat filtered, appx 50% PWC's every few days is over *500 microsiemens*!!

Regani is right, there has to be a source of cations in the tank (like calcium carbonate in shells, limestone etc) for the conductivity to rise so much in the tank.

You also have to note that the H+ ions exchanged by the peat will also contribute to the conductivity (again thanks to Regani's explanation in this post <http://www.apistogramma.com/forum/index.php?threads/700-liter-amazone.13197/#post-71427>), although humic compounds may chelate some of the ions (again in the "700 liter" thread where citric acid is mentioned as reducing conductivity).

cheers Darrel

 

[gerald]

I agree with everything Regani and Darrel said. Keep in mind that:
1) pH and conductivity are entirely independent. You can have high or low pH at any conductivity.
2) Hard water will have high conductivity (due to its Ca and Mg ions) but soft water can have any conductivity. You can add heaps of Na, Cl, K, SO4, NO3, CO3, and other ions without raising the GH hardness measurement.

 

[JasonC]

Thanks for the responses... the mention of organic material got me thinking.. .there is a handful or two of Amazon Frogbit sitting on top of the water that is not responding well and I am getting a lot of die-off... I assume the rotting leaves could have something to do with it? The only other things in the tank are PFS substrate and some Indian Almond leaves... I doubt any of these are a source of ions? I will check my water in the morning and report back on GH... havent had much time at home in the past few days due to work.

So peat filtering can take care of some of the KH, but when it comes to lowering GH, what are my options?

Also, if pH and conductivity are completely independant, what should I be looking at and worrying the most about when it comes to adjusting water parameters? So much to learn ;P

 

[dw1305]

Hi all,

the mention of organic material got me thinking.. .there is a handful or two of Amazon Frogbit sitting on top of the water that is not responding well and I am getting a lot of die-off...

It won't be the Amazon Frogbit dieing off, although any decay will lower the oxygen levels in the water. I'm suprised your Amazon Frogbit is dieing however, as it is fairly indestructible if it gets enough light.

PFS substrate

I don't know what this is, but if this is a "complete substrate" (containing fertilisers) that will be the source of the ions.

So peat filtering can take care of some of the KH, but when it comes to lowering GH, what are my options?

Peat will lower GH rather than KH, as the H+ ions are exchanged for Ca++ ions etc. You could use an ion exchange resin (which you re-charge with NaCl) to swap Ca++ ions for Na+ ions, but I wouldn't recommend this. If you re-charge the ions exchange resin with KCl it will exchange K+ ions for Ca++ ions which may be preferable if you have plants (plants will take up K+, but not Na+ ions, which is why the sea contains all that sodium).

Also, if pH and conductivity are completely independant, what should I be looking at and worrying the most about when it comes to adjusting water parameters?

They aren't completely independent, but Ted Judy has done some work that shows that pH is more important than conductivity. Details here: <http://www.apistogramma.com/forum/index.php?threads/ok.12048/>.

cheers Darrel