Math question for 1st water change in about 2 years

[stang8s]

I have noticed the last week my BTA has not looked happy and today i tested salinity to be low at only 1.020 @76 Deg on my refractometer. ( i added a cup of salt to my top off water container and about a 1/2 cup into the sump doubt either changed anything much) I decided perhaps i should do a waterchange.... First in about 2 years.

I have mixed up aprox 30 gallons of water at room temp which is aprox 66deg and it reads aprox 1.028 on my refractometer...

So if i change that into my 75gallon tank (aprox 75 true capacity with sump/fuge) What would my resulting salinity/temp be and would it be too much of a shock to my system. I maybe able to scrape up a heater to warm it up 1st. Still digging.

System is mostly soft corals, 1 LPS, 1 BTA, snails,crabs,serpant stars, fish. NO sps.

 

[MikeG]

I have noticed the last week my BTA has not looked happy and today i tested salinity to be low at only 1.020 @76 Deg on my refractometer. ( i added a cup of salt to my top off water container and about a 1/2 cup into the sump doubt either changed anything much) I decided perhaps i should do a waterchange.... First in about 2 years.

I have mixed up aprox 30 gallons of water at room temp which is aprox 66deg and it reads aprox 1.028 on my refractometer...

So if i change that into my 75gallon tank (aprox 75 true capacity with sump/fuge) What would my resulting salinity/temp be and would it be too much of a shock to my system. I maybe able to scrape up a heater to warm it up 1st. Still digging.

System is mostly soft corals, 1 LPS, 1 BTA, snails,crabs,serpant stars, fish. NO sps.

How about changing water with the same salinity and then topping off with salt water instead of fresh water until you bring it back up? I would be hisitant to bring it up .004 or so real fast.

 

[stang8s]

Yea that is probally what i will/should do. Wasnt sure with the temp difference how large the salinity difference really was? Isnt salinity different at different temps or does the refractometer somehow not effected by that?

 

[jazzsam]

How about changing water with the same salinity and then topping off with salt water instead of fresh water until you bring it back up? I would be hisitant to bring it up .004 or so real fast.

That is how I raised my salinity and it worked great for me.

 

[Troubleman]

Isnt salinity different at different temps or does the refractometer somehow not effected by that?

Depends on which refractometer you have, some older ones you will have to mathmatically adjust for temp. most newer ones are self calibrate with changing temp.

 

[stang8s]

i checked and its a ATC model (auto temp correcting).. thanks

 

[Cardiak]

I dont see the need to up the salinity all at once, you could easily shock something in there. I'd just slowly add salt with your top off water and check it ocasionally untill its where you want it to be.

 

[stang8s]

Yep thats what im doing. thanks