Why test conductivity?

[Anna Piranha]

I am curious to know 2 things:

1) Under what circumstances would a person have to check conductivity? Breeding? Raising Fry? Curing disease?

2) What kind of a test or instrument do you need to test it?

Any info would be helpful,
Anna :book:

[roger]

I have always thought that conductivity was a very rough way to measure things. Most conductivity meters cant tell you whats causing the conductivity to go up. I use both the cheapo chemical drop test kit to figure gH and kH then the meter to do spot checks.

The only times that I can think of that conductivity makes a difference is when your trying to breed the fish and then raise the fry. When the eggs are laid you want low conductivity ie soft water, but when you raising fry you want harder water. The harder water provides much needed minerals to the little tykes to make em grow.

The other time that conductivity is usefull is for checking to see if the RO water that your using is really RO water :)


You can get a cheapo test kit for 5-10$ and its about 20$ for a little hand held meter. Check with RandalB I think for the meter.

Peace,
Roger

[Discusgeo]

Conductivity or specific conductance is the measure of the water's ability to conduct an electric current. Conductivity depends upon the number of ions or charged particles in the water. The specific conductance is measured by passing a current between two electrodes (one centimetre a part) that are place into a sample of water. The normal unit of measurement for conductivity is expressed in microsiemens per centimetre (µS/cm) or millisiemens per centimetre (mS/cm) . Conductivity meters are calibrated with a Potassium chloride solution. I use a low conductivity of 70-100mS when breeding my Discus

Water Hardness

Hardness is commonly confused with alkalinity. The confusion relates to the term used to report both measures, milligrams per litre as calcium carbonate (mg/L CaCO3). Calcium carbonate is a general term that indicates the total quantity of divalent salts present and does not specifically identify whether calcium, magnesium and/or some other divalent salt is causing water hardness. Calcium and magnesium ions are the most common factor that comprises hardness and aquarium test kits usually determine both ions as "total hardness". Despite the much confused state of misinformation prevalent in the hobby, permanent or general hardness is true hardness; carbonate hardness (dKH) is not
hardness at all but alkalinity. Hardness should be expressed as a concentration of divalent ions in mg/L (ppm). The permanent", "general", and "carbonate" hardness should be discontinued.

Calcium and magnesium are essential in the biological processes of fish (bone and scale formation, blood clotting, and other metabolic reactions). Fish can absorb calcium and magnesium directly from the water or from food. The major organs used are the gills for absorption and the intestine along with the kidneys. Calcium is the most important divalent salt in rainbowfish culture water and is maintained in the blood at levels higher than the environmental level. The presence of calcium in aquarium water helps reduce the loss of other salts; for example, sodium and potassium from the fish's blood.

Sodium and potassium are also important salts in fish blood and are critical for normal heart, nerve, and muscle function. Research has shown that environmental calcium is also required to reabsorb these lost salts. In low calcium water, fish can lose substantial quantities of sodium and potassium into the water. However, it is not clear whether calcium plays an equally important role in embryonic development. A recommended range for free calcium in culture waters is 25 to 100 mg/L (50 to 250 mg/L CaCO3 hardness). A low CaCO3 hardness value is a reliable indication that the calcium concentration is low. However, high hardness does not necessarily reflect a high calcium concentration.

Water hardness is expressed in a confusing array of scales, although in the aquarium hobby the influence is to express them in terms of milligrams per litre of Calcium carbonate (mg/L CaCO3), which is also equivalent to parts per million, and degrees German Hardness (dH). For aquarium purposes, you can use the following conversion factors: dH × 17.9 = ppm
ppm × 0.056 = dH

Dissolved Solids:
Total dissolved solids (TDS) is a measurement of the total amount of dissolved substances in water and expressed in ppm of NaCl. TDS is essentially the same as conductivity. For aquarium applications it is recommended that the conversion formula TDS (in ppm) × 0.64 =EC (in µS/cm) be used. The conversion formula is only an approximation. TDS meters are calibrated with a Sodium chloride solution.

Copyright Adrian R. Tappin
Updated December, 2000.

[Anna Piranha]

Thanks for posting this George. It clears some things up and makes some other things fuzzier. I understand now why if one were to begin a breeding program, you would want to understand and, if necessary, manage this factor. I am tempted to draw the conclusion that low conductivity (e.g., the author's example of 70-100mS) indicates higher calcium and/or magnesium content. I am not in the least tempted to begin a breeding program, however. Too new to the scene! Thanks again!

Anna :book:

[black rat]

Discusgeo,
I note that you breed between 70-100ms,
do you find that this range gives the best hatch rate?
Or does the hatch rate decrease with the lower reading? ???

[Discusgeo]

I found that most of the eggs will hatch at this rate for me. But you have to remember that the eggs won't hatch if the male did not fertilize them to begin with. I also add 2 drops of Formalin per gallon to reduce fungus growing on the eggs but it does not prevent that from happening to all of them.
George

Anna, It is just the opposite. Low conductivity--means LOWER amount sof calcium and magnesium -- necessary nutrients for skeletal development . Joe

[black rat]

:D

Roger, conductivity rises with additions of conditioners, buffers and trace elements. I find a conductivity meter is helpful for pinpointing the parameters for grow outs as well. I like the accuracy --not found in the cheapo reagent or dry tab test kits. Also they keep ringing you up in costs as a precision meter will last a long time. No other meter will tell you why certein values have risen or fallen either--so I do not understand your post--please explain? Thanks, Joe ;)

[Anna Piranha]

Hi Joe,
Thanks for clearing this up for me. I assumed that if calcium and magnesium are necessary for skeletal growth, then having them in greater concentrations would be important for developing fry. In the article, the author referred to lowering these values for breeding. I was confused by that - why would you want lesser concentrations? So I concluded that lowering the values actually had something to do with increasing concentrations of just those elements. I think I was working too hard to understand it all. I should just have accepted it at face value, which as you said is - lowering conductivity means lowering calcium and magnesium content. Still not sure why you would want to do that at breeding time, but I am willing to trust the experts on this matter. After all, chemistry was not my forte :inquisitive:

Thanks again!
Anna

Anna, Higher concentrations of calcium and magnesium add to the hardness. To have the best hatchrate, since eggs develop better in softer water ( low conductivity ) Figuring that the babies will be typically left with the parents for two weeks, the water for their temporary stay can be adjusted slowly towards theend result--- the need for more mineral content for optimum growth. :) Joe

[Anna Piranha]

Ok! It's starting to sink in! Thanks for staying with me on this one, Joe. I'm further along in my understanding because of your help :idea:

[hunterbeav]

Lol Anna when spawing my discus I keep the water at 80ms PH 6.4 and water temp between 81 and 83deg. After the fry hatch I add tap water in to bring up the hardness of the water. That way the babie fish can develope, they need calcium and other minerials to grow big and strong lol. As far as adult fish go, I just keep them in my tap water which is at about 700ms. Just figured I'd add my nickels worth Jim & Diane :)

:o :o :o :o :o :o :oHunterbeav---Adult fish at 700mS???????????????????/ :o :o :o :o :o :o :o :o :o :o :o :o
They must surely look good?
How about getting the coast guard ice breaker? Do they have anything resembling a slime coat??? :P Joe

[April]

wow....i cant even imagine 700 ms. as my tap water is 30 ms. needless to say..i have to add stuff to get my hardness up..or i get very poor growth.
i think i need a truck to backup to my doorstep to drop off the calcium and magnesium and salts to get my water that hard..

[papagimp]

anybody know the conversion from micro-semiens to something I could read on a voltmeter? I test for conductivity at work with electrical currents but not in MS.

[steve.ryall]

Going back to the low conductivity-hatch rate question. It is believed that the softer the water when the eggs are laid, aids the males sperm to penetrate the eggs easier, therefore you will get a higher fertilization rate. If the water is too hard the eggs, as soon as they are laid, get a 'harder' outer skin to them which makes it more difficult to fertilize.

HTH

Steve