Effects of high SG and how to safely lower it?

[flanque]

Hi,

My specific gravity is at around 1.030 which is a little high. Firstly, what does this do to the inhabitents?

Secondly, how can I safely reduce it? I know I have to add freshwater, but how does one calculate how much to change, over what period of time and any other special considorations in doing so?


Thank you.

 

[ZoozFishMaster]

Fish expend more energy at higher salinities than at lower salinities(osmoregulation). Lowering the specific gravity of the tank can be done (safely) a lot quicker than raising it. I would shoot for .001 per day. HTH

 

[flanque]

Okay but how does one calculate reducing it by that rate? For instance, how much would someone with a 10L bucket know by how much that reduces the salinity per bucket?

 

[fishfreek]

How are you testing this water? Are you using a hydromoter or a refractomotor? I wouldnt classify 1.030 as being to overly high and you can easily bring it back in line by taking out a few gal of salt water and adding a few gal of fresh. How do you calculate how much to remove? Well Im sorry but I dont konw that much math to be able to figure up a formula but I can tell you to do it slowly over a few days and I would suggest taking out 1 gal of water from the tank and adding 1 gal of fresh to the tank on day 1. Then on day 2 check your salinity and see what the change was. If the new salanity is 1.027 then you know its safe to remove another gal of water from the tank and add another gal of fresh. If the new salanity is less than 1.027 then you might want to take out only a half gal of saltwater and add a half gal of fresh.

 

[ZoozFishMaster]

This is how you calculate. For instance, let's say you do a five percent water change with just freshwater.

1.030(.95) + 1.000(.05) = 1.0285

Alright, lets try a ten percent change with freshwater.

1.030(.90) + 1.000(.10) = 1.027

Still not enough, how about twenty percent with freshwater.

1.030(.80) + 1.000(.20) = 1.024


As you can see, you will need to take out about 20% of your tanks volume and replace with freshwater to attain a specific gravity of 1.024. You do not want to do this all at once. Taking out 5% and replacing with freshwater lowers the SG about .0015 (as shown in the first calculation). I would take out about 5% of the water and replace with freshwater, everyday for about 4 days. (you may actually need to do this for five days, because we did not account for evaporation, which is constantly raising the SG). HTH