Water changes

[nobody]

What percentage should the water change be every two to three weeks. I have a 125 gal. With 30 gal sump. Lots of rock so maybe 110 gals. Total water. Suggestions.

 

[Bifferwine]

10% weekly or 20% every other week. You don't subtract the water displaced by the rock -- it's less than you think.

 

[nobody]

I have mixed up 14 gals. of RO water and added 7 cups of salt as per instructions. I checked the SG and it is 1.19. Means I need to bring it up more. Is that correct? Any idea of how much to add? And should I add more and get the SP up to .23?

 

[bjohanson1234]

I have mixed up 14 gals. of RO water and added 7 cups of salt as per instructions. I checked the SG and it is 1.19. Means I need to bring it up more. Is that correct? Any idea of how much to add? And should I add more and get the SP up to .23?

I would double check your number there. It should be around 1.024 or so. If it is 1.19, it is too high. I think you have a typo, but it is best to double check.

 

[Bifferwine]

You probably meant 1.019, right? If so, yes you need to raise it. The instructions on the back of the salt package aren't exact. You will normally have to add more salt or more water to get it just right. I would just add another scoop or two, stir it, let it sit for a bit, then re-measure the salinity. It doesn't have to be perfect. If you consider the overall volume of the tank, the water change is not a lot, so the salinity of the new water being slightly off isn't going to hurt anything. Just as long as it's close.

 

[nobody]

You both are correct. I did mean 1.019. I added 1/2 cup and it raised it to 1.020. So I guess I should add a little more? What is the ideal number I should try to achieve? My tank is reef and fish. And it has IMO been running kind of low at 1.02.

 

[FishyReef]

You should stick a powerhead in your mixing bucket and run it for several hours (preferably overnight) to really let all of the salt dissolve, then measure it again. 1.02 is super low - that's not even in the brackish range. For a reef tank you need 1.024-1.026. If you have fish/inverts/corals in your tank already, and your tank salinity is on the low side, then you need to bring it up slowly, about .001 per day. And what are you using to measure your salinity - hydrometer or refractometer? Hydrometers are notorious for being really inaccurate...

 

[yote]

An easy way to raise the salinity,is to just use salt water for your daily top-off.
But you need to check the salinity daily too. Just to make sure you don't over shoot it.

 

[nobody]

I thought it was low. I use a hydrometer so I guess I will check on a refractometer. I will try using a salt mix to top it off each day and slowly raise it. I do have a powerhead in the mix tank and also am running a small filter.