Confused with live rock

[Pseudomugil]

Now I need help with water changes. If I took out 10% weekly (this is a 20 gallon tank), how do I know what salinity to put the new water at? Because in a small container for mixing the new water, wouldn't the salt be less in the tank?

Do I put the new water at the same salinity as the tank water?

 

[dylan p]

You just match it to the new water. The water you take out won't change the salinity in your tank. If your changing evaporated water you just add fresh water because the salt doesn't evaporate. Thank god to because if it did every time it rained there would be salt everywhere


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[Pseudomugil]

You just match it to the new water. The water you take out won't change the salinity in your tank. If your changing evaporated water you just add fresh water because the salt doesn't evaporate. Thank god to because if it did every time it rained there would be salt everywhere


Sent from my iPhone using Aquarium Advice

Ok thanks that makes sense

 

[mr_X]

You should invest in a refractometer and not rely on a swing arm hydrometer. This is the only way to be sure you are adding the correct SG water back to your tank.
BTW, if you plan to add hermits and snails to your tank just after the cycle, make sure you put food in the tank for them. Don't expect that there will suddenly be enough food in the tank to sustain them.

 

[jeffaquarius]

You should invest in a refractometer and not rely on a swing arm hydrometer. This is the only way to be sure you are adding the correct SG water back to your tank.
BTW, if you plan to add hermits and snails to your tank just after the cycle, make sure you put food in the tank for them. Don't expect that there will suddenly be enough food in the tank to sustain them.

A reef keeper can make a choice to set his tank salinity between 1.024 to 1.026. If one uses a swing arm hydrometer and he reads the salinity of the tank exactly the same as that of the salt water to be added would that really matter as far as accuracy is concerned?

 

[Mebbid]

A reef keeper can make a choice to set his tank salinity between 1.024 to 1.026. If one uses a swing arm hydrometer and he reads the salinity of the tank exactly the same as that of the salt water to be added would that really matter as far as accuracy is concerned?

The only problem is that swing arm hydrometers are notorious for giving different reading taken from the same water. I know mine did that exact thing. For some people it's accurate enough, but I like to know for sure.

 

[melosu58]

FAQ's Regarding Live Rock

 

[jeffaquarius]

The only problem is that swing arm hydrometers are notorious for giving different reading taken from the same water. I know mine did that exact thing. For some people it's accurate enough, but I like to know for sure.

Let's assume one doesn't know how to use a salinity tester regardless if it's a notorious one or accurate one and the salinity of new salt water has a difference of 0.001 with the tank (which is by the way a worse case), what do you think is the effect when you replace 10% of it?

 

[Mebbid]

Let's assume one doesn't know how to use a salinity tester regardless if it's a notorious one or accurate one and the salinity of new salt water has a difference of 0.001 with the tank (which is by the way a worse case), what do you think is the effect when you replace 10% of it?

My instant ocean hydrometer had a .003 difference when readings were taken less than a minute apart. Assuming a 10% water change, I wouldn't really worry about a .003 difference. However, if I am drip acclimating inverts a .003 difference can and probably will kill them. Hence, why I chucked my hydrometer and bought a refractometer for less than the price of a shrimp.

 

[jeffaquarius]

My instant ocean hydrometer had a .003 difference when readings were taken less than a minute apart. Assuming a 10% water change, I wouldn't really worry about a .003 difference. However, if I am drip acclimating inverts a .003 difference can and probably will kill them. Hence, why I chucked my hydrometer and bought a refractometer for less than the price of a shrimp.

Refractometer needs to be calibrated so often and it will also give you false reading at the wrong temperature. I never have a problem with swing hydrometer. In fact I switched from refractometer to swing. The trick is to swing it several times until it stabilizes and settles down.

 

[Mebbid]

Refractometer needs to be calibrated so often and it will also give you false reading at the wrong temperature. I never have a problem with swing hydrometer. In fact I switched from refractometer to swing. The trick is to swing it several times until it stabilizes and settles down.

I undestand perfectly how to use a swing arm hydrometer. Mine did not give consistent readings no matter what i did.

My refractometer on the other hand has always been consistent. Its still perfectly calibrated after a year and a half of use. Even if it wasnt calibrated it will still give consistent readings.

 

[jeffaquarius]

I undestand perfectly how to use a swing arm hydrometer. Mine did not give consistent readings no matter what i did.

My refractometer on the other hand has always been consistent. Its still perfectly calibrated after a year and a half of use. Even if it wasnt calibrated it will still give consistent readings.

A bad test equipment doesn't justify a conclusion that they are all bad and unreliable. A bad swing arm hydrometer is as bad as a defective refractometer.

 

[Mebbid]

A bad test equipment doesn't justify a conclusion that they are all bad and unreliable. A bad swing arm hydrometer is as bad as a defective refractometer.

That's a fantastic point. However, when you spend $12 on a hydrometer that you later find out is completely inaccurate which confirms exactly what dozens of people have been telling you about them; are you going to go and spend another $12 on a second hydrometer or are you going to instead spend $25 on an refractometer which the entire reefing community trusts?

How about test strips? Are you going to use them later to find out they are inaccurate then go out and buy more just in the hopes that the next batch will be better despite the reefing community telling you otherwise?

With the minuscule difference in price between a refractometer and hydrometer why would we trust hundreds to thousands of dollars in living creatures to save $13?

 

[mr_X]

I tested water with 2 swing arm hydrometers and one said .021, and the other said .030.....hardly a couple points. Just sayin!

 

[jeffaquarius]

I tested the same water with a refractometer a few minutes apart and the reading is not consistent. Can anyone explain why?

 

[Sniperhank]

Usually air trapped on the swing arm.

Either way, the OP's question has been answered at this point and we are quite off topic. Thread closed.