The Puffer Forum

if my tank is 154 litres and at 1.0004 salinity, when i do a 50% water change every 2 week of 77 litres.
at what salinity would i make the 77 litres im putting back into the tank to finish up with 1.0004 in the tank again.
if some 1 good help me on this then that would be amazing, cheers.

I assume that you mean SG1.004. But yeah you're just matching what you already have, it's when you wish to change the salinity that you would prepare the new water with a different salt content. There's a post on this forum by Dadof4 that shows the maths involved

oh i understand, so putting 77 litres at SG 1.004 with 77 litres at SG 1.004 as well, will not change the reading of the SG just the mass of water to 154 litres to fill the tank.
is that right? and thank you for your reply.

If your replaceing the water that you took out with the same SG then yes your salt gravity will stay the same in your tank. If your wanting to raise it then you can use this method.

starting SG of 1.004, do a 50% water change with SG1.008 this will put your ending SG in your tank at 1.006.

If you do a 50% water change and just add 1.004 more then what your tank is the extra salt will balance out makeing your SG raise 1.002 more then what it was before.

1.004 > 50% water change with 1.008 > end SG in your tank will be 1.006

1.006 > 50% water change with 1.010 > end SG in your tank will be 1.008

And so on and so on. Its fairley easy if you keep your water changes at 50%. The extra 1.004 will dispurse in your total water valume equalizeing out at 1.002 more then what you started at. Hope this helps and isnt too confuseing.

There is an article on BW mixing, stickied in this forum.

thank you that all helps a lot and i understand now, cheers guys