Can I add sea salt to my freshwater tank instead of epsom salts?

[charlieborg]

I have left over sea salt from a marine tank. Can I use it in a fresh water tank instead of Epson salts?

 

[NickAu]

No and why are you adding Epsom salt to your tank?

 

[StevenF]

Epsom salt is magnesium sulfate. Sea salt is mostly sodium chloride, along with calcium and magnesium chloride, potassium chloride and other halide salts. They have very different properties and uses.

 

[charlieborg]

No and why are you adding Epsom salt to your tank?

I have African cichlids in my tank, I want the water to be close to what they live in.

 

[StevenF]

This is what you want. Keep in ind that for most people"salt" means sodium chlorine. However for a chemist "Salt" refers to a byproduct of a reaction between and base element and an Acid.
http://www.seachem.com/cichlid-lake-salt.php

 

[Byron]

I have African cichlids in my tank, I want the water to be close to what they live in.

First, what are the parameters of your source water (tap or well, whichever), meaning GH (general hardness), KH (carbonate hardness or Alkalinity) and pH? You may not have to change. There are proper rift lake salts--and "salts" used here refers to several mineral salts not "common salt." There are less expensive and better solutions, such as using an aragonite-base sand (not marine sand which again has common salt).

Second, neither Epsom Salt nor Marine Salt will provide water suitable to rift lake cichlids (I am presuming "African" to refer to the fish from the rift lakes, not the soft water species like the kribensis). Steven has mentioned the composition of both; the Epsom Salt lacks the calcium essential to the physiology of these fish, and the Marine Salt includes sodium chloride (commonly thought of as "salt") which is not beneficial for freshwater fish and the higher the level the more detrimental it becomes.

Edit. Steven posted as I was typing this, and he has linked one rift lake mix. I personally would not go this route as it means always having to prepare the water for water changes. A calcareous sand substrate is simpler.

Byron.

 

[StevenF]

I personally would not go this route as it means always having to prepare the water for water changes. A calcareous sand substrate is simpler.

If you look at the Sachem website I posted a link to earlier they say:

Dosages are based on DI or RO water; for other water, measure hardness (GH) first, then add according to need. For reference, the Tanganyika dose raises dGH by 8.8 units. The Malawi dose raises dGH by 4.4 units. The Victoria dose raises dGH by 3 units.

We recommend the following GH ranges:

• Tanganyika: 3–5.5 meq/L (8–14 dGH)
• Malawi: 1.5–3meq/L (4–8 dGH)
• Victoria: 1–2 meq/L (3–6 dGH)

A Calcarious substrate is mainly calcium carbonate and or calcium sulfate These calcium salts are barely soluble in water with a PH of 7. You might be able to reach a DGH of 4 but anything more is going to be very difficult to impossible. If you look at the Sachem ingredient list:

Ingredients: magnesium chloride, calcium chloride, potassium sulfate, sodium chloride, aluminum sulfate, iron sulfate, potassium iodide

Calcium chloride and magnesium chloride is highly soluble and will get you beyond a DGH of 8. Unlike the calcium carbonate or sulfate which are barely soluble. All of these calcium and magnesium salts are safe for fish as long as you keep the gh in a range the fish can tolerate. Also according to the seachem product link is heavy in magnesium. A Calcarious substrate will give you a Calcium rich substrate. Also a Calcium substrate will not give you the appropriate potassium, sulfate, sodium, aluminum, iron, and iodine levels.

http://www.seachem.com/cichlid-lake-salt.php


In this case I don't agree with Byron because of the low solubility and chemistry of calcium substrates.

 

[Byron]

I guess I need to explain myself better. But I was waiting for the OP to provide data on his source water since none of this may be necessary. Nevertheless, by "calcareous" I actually meant something like CarribSea's aragonite sand, which has calcium and magnesium. This is (so far as I know) the basis of their marine substrate but without the salt (sodium chloride). I have some of the aragonite and it has worked for me.

 

[StevenF]

I have some of the aragonite and it has worked for me.

the problem with carbonates such as aragonite is that there solubility is dependent on water PH. IF the PH is above 7 it will not resolve. If the PH is below 6it will partially dissolve. Below 5 it is almost completely soluble. Between a PH of 6 and 7 the solubility of about 11mg per liter. Which is less than 1 degree GH. Magnesium has about the same solubility as calcium so together calcium and magnesium carbonate will be about 22 mg per liter, or slightly more than 1 degree GH.

The only way to get it to resolve is to saturate water with CO2. But that makes the water too acidic for fish. So if your PH is close to 7 and you need a DGH of 4 Calcium and magnesium carbonate is not going to get you there. You might get to 2DGH but that is about it.

As to testing the water that is the first step and that is indicated in the Sachem link i provided.