Salinity/sand/freshwater

[WhiteDevil]

Quick question.

Is it true that sand does raise the salinity of the water as well?

MY LFS who also takes care of our 2 9k tanks at work, said that the real fine sand can and does raise the salinity and asked me for a sample of water due to misleading statements from other LFS's and a sample of my sand for a 24 hour salinity test....


I am going to do it but I am also in hopes that if it is high enough that I can have brackish fish in there as well. My tetras are able to withstand the salinity and so do the angels. Is this possible?

 

[AMDPhenomX4]

Aslong as its washed well it shouldnt. Either way the sand should be washed when harvested or made.

 

[newfound77951]

I don't see how sand could raise salinity unless it had been in saltwater and was not rinsed, and even then it would only raise salinity for a short time, the effect would not continue.

Depending on the composition of the sand, it can certainly affect other water parameters such as pH and carbonate hardness. However these are completely separate from salinity, which is a measure of the amount of salts in the water. Quartz sand is for all purposes inert, while aragonite sand is calcium carbonate and will increase pH and hardness.

 

[jsoong]

It comes down to semantics ....

Strictly speaking, salinity is a measure of salt content ... and salt is not just NaCl ... the common table salt that tastes salty .... All kinds of ions are also salt. eg Ca++, Mg++, etc. all contribute to salinity in a marine environment.

To avoid confusion, however, salt (chemical salt, not common salt) content in FW is better called TDS (total dissolved solids). This would include any NaCl, KH, GH & any other stuff dissolved in the water. TDS is also called osmolarity & is what the fish sees. <Within reason, FW fish don't care a hoot if the osmolarity comes from Na or Ca ....>

To answer the question, if the definition of "salinity" is the concentration of chemical salts, then yes, sand can certainly raise it.

To avoid confusion, I can say this instead: Some sand (CaCO3 - eg aragonite) will increase the TDS of your water.

 

[WhiteDevil]

Its THIS sand

Except its white. same brand.

She said something about a 24 hour test to see if it does raise the salinity, basically she is taking MY sand NO NO NO WATER FROM MY TANK, and using her 7.0 perfect PH water to see if and how much the chemical make up of HER water reacts to MY sand to give me that result.

One LFS said I have discus perfect water, I told her this with the expression of i think the info is wrong, and she said that its impossible for me to have the PH for discus with the substrate I am using which is sand.

 

[jsoong]

she said that its impossible for me to have the PH for discus with the substrate I am using which is sand.

I think she is wrong ... there are totally inert sand that will not change the GH or pH. It all depends on the composition of the sand. <Sorry, don't know what is actually in that brand you have .... but a simple test is to put some in distilled water for a day or 2 & measure the GH, KH & pH before & after.>