Water changes

[Redrider]

@Redrider from what I am inferring you're having difficulty achieving a desired specific gravity. You state your water seems to be a constant 1.020 and yes you are doing as instructed.

I would imagine your evap rate might be perhaps around a gallon a day +/- and you are using the RODI fresh to top off which is the correct thing to do however it would remain at the 1.020 range.

A simple way to slowly increase the level you desire say 1.023 to 1.026 can be done by doing the top off with the salt water of your choice whether it be the Catalina NSW or ASW until you have slowly safely reached where you wish to be and once there cease the top off with the saltwater and resume adding the correct top off using the RODI fresh water. I'm kind of wondering why your LFS did not suggest this to you.

When it comes time to do whatever water percentage you wish to do ensure you remove exactly the gallons you wish and use the ASW or the Catalina NSW at the same salinity level as that which you have achieved to get avoiding the fluxes and shock of drastic swings. Your pH will start to balance as well.

I hope this made sense.

AND, if it were opposite...say you added too much saltwater with a higher range accidentally you could dip out and use RODI fresh to get back to your normal rate.

I hope this helps and it is pretty much what others have suggested just in a simple form. Please keep us advised on your progress because we want to see you enjoy a nice healthy system with happy fishes.

~Best Regards~

Thank you for the response.
I guess I didn’t articulate very well in this post.
I did a water change 7 days ago. Since that water change I have been topping off approximately 1 gallon per day. I have a mark on the tank which corresponds to a level in the return pump section of the sump where I see the water barely swirling as it gets sucked into the pump.
Also, the LFS agreed with my decision to top off with saltwater exclusively until I reached a salinity value capable of supporting coral. As an aside, I’m not ready to tackle coral right now. Maybe later if I can keep the critters alive long term.
Even with this tact of topping off with saltwater, my water is still coming out low.
My plan now:
I’ll be transferring all except the livesand from the 90 to the 120. At that time, I should be able to raise salinity. Fresh Catalina water (40gallons)will hopefully give me 1.023.
I’ll be happy if I can get it stabilized at that value and return to the RO/DI and add buffering if necessary for topping off.

 

[lapin]

Great point my friend. I top off what is lost in the cup with small amounts of saltwater for the balance.

I go thru about 4 gallons of top off water per day. 28 per week, of that, around 6 gal is skim water. Since I have 600 or so gallons 1% does not make much of a difference in salinity.