Low SG

[Mr. Microscope]

Hello all,

 

So I've been checking my SG everyday and it seems is consistently a low (1.021-ish). I just started the tank last weekend and I wouldn't be so concerned, but I have some pretty cool HH in my tank including a small patch of GSP that came on one of my rocks. I especially don't want to kill these off.

 

The directions on the salt says 1.023 is good, but I've seen other posts talking about 1.025 being the SG of ocean water. Also, I am using a hydrometer and not a refractometer (Yes, I know..I'll get one soon). I understand how temp affects SG and that these things are only accurate at 80F. Actually, my temp is a little lower than 80 (78ish), which means it is actually lower than 1.021.

 

Any thoughts? Should I add a gram of salt to the fuge?

 

Thanks in advance.

[pisces4u]

I wouldn't add dry salt to the system. You can add saltwater as top-off instead of freshwater to cover evap for a day or two.

 

I would get the water checked by someone with a properly calibrated refractometer before you act.

[nanoreefnate]

I wouldn't add dry salt to the system. You can add saltwater as top-off instead of freshwater to cover evap for a day or two.

 

I would get the water checked by someone with a properly calibrated refractometer before you act.

 

+1 get a refractometer. what ur hydrometer is reading right now is probably wrong anyways.

[Mr. Microscope]

What do you guys think about SG. 1.023 or 1.025?

[Mr. Fosi]

+1 get a refractometer.

 

Or just calibrate your hydrometer with someone else's refrac and save yourself the $40.

 

Doesn't matter. Either one is fine.

[nanoreefnate]

1.025.

[Mr. Microscope]

Is 1.021 really bad, or just on the low side? What kind of effects will low SG have on the life in my aquarium?

[SK8URDEAD]

Is 1.021 really bad, or just on the low side? What kind of effects will low SG have on the life in my aquarium?

 

they will live, but its better to have your salt at a 1.025 for better results. the bags say for a 1.022 but we all mostly have it set at 1.025 make our corals more happy, other reasons i dont know 0_0

[Mr. Microscope]

I wouldn't add dry salt to the system. You can add saltwater as top-off instead of freshwater to cover evap for a day or two.

 

How would this hurt? Could I do it a little at a time in the back of the fuge? It sure would be easier than mixing up new water (not that I entered this hobby cause it's easy..but..you know..)

[SK8URDEAD]

How would this hurt? Could I do it a little at a time in the back of the fuge? It sure would be easier than mixing up new water (not that I entered this hobby cause it's easy..but..you know..)

 

well addint salt to the tank can shock the fish/corals. also your main goal is to get the SG to par. so the main goal is to mix the salt in new batch of water, get it higher to the level you want and add to the tank. because salt takes a while to dissolve and if you just throw it in the tank you wont know till like a hour later if you are way over the sg level.

[Mr. Fosi]

How would this hurt?

 

Shock, mostly.

 

1.021 is really too low. Aside from isotonic issues, you won't have the alkalinity, Ca, Mg or any other mineral concentration that the salt is designed to produce.

 

Mix it up to the manufacturer's spec unless you have a good reason for not doing so.

[Mr. Microscope]

Cool. Are there any tables or calculators out there for mixing water with different SGs? So, far I've been crunching numbers whenever I add or change anything and, so far it's been working (the biggest challenge is working from standard to metric..sigh). I don't want to guess on this one.

[johnmaloney]

Or just calibrate your hydrometer with someone else's refrac and save yourself the $40.

 

Doesn't matter. Either one is fine.

You should have a thread "how to save thousands", poor marine depot, (sorry guys you are just the 1st dry goods place that came to mind), wouldn't know what hit them.

[goSJSharks]

At some point, my salinity was kind of low, and I topped off with salt water for a few weeks. It was during a cycle, and I didn't have to waste any existing water, nor did I have to worry about a drastic change in salinity (topping off maybe 3% max at any given time).

[Mr. Fosi]

Are there any tables or calculators out there for mixing water with different SGs?

 

Your brain.

 

It is dependent upon the salt you're using. I always used 0.5 cup salt to 1g water. Of course, the volume of the salt would change over time as it adsorbed water, but that was fine. I just checked it with my hydro when done and amended if I had to (not usually).

 

John: I'm really about as cheap as they come.

 

I know refractometers are nice but I'm not spending $40 on a bit of equipment I don't need and that needs calibrated regularly. I use them in the lab and in the field but I just can't justify personally owning one because my Instant Ocean swing-arm hydrometer does just fine... And I've dropped it who knows how many times. It's chipped, the lip is cracked and one of the sockets that holds the arm in place is missing the bottom half but it still reads right every time. In 4 years it hasn't varied (checked against calibrated refractometers). There is no refractometer out there than can beat that.

[cruiZe]

...In 4 years it hasn't varied (checked against calibrated refractometers). There is no refractometer out there than can beat that.

Sad to say, my $40 refracto now randomly swings from 1.025 to 1.040 and must be calibrated back every time I use it. and its only 2 months old..

[Warehouse41Ant]

<---- This guy needs to check his calibration. I was under the impression (largely from what I've read on N-R) that refractometers were better and needed very LITTLE calibration. Guess I'll have to look into that.

[papajohn40]

Your brain.

 

It is dependent upon the salt you're using. I always used 0.5 cup salt to 1g water. Of course, the volume of the salt would change over time as it adsorbed water, but that was fine. I just checked it with my hydro when done and amended if I had to (not usually).

 

John: I'm really about as cheap as they come.

 

I know refractometers are nice but I'm not spending $40 on a bit of equipment I don't need and that needs calibrated regularly. I use them in the lab and in the field but I just can't justify personally owning one because my Instant Ocean swing-arm hydrometer does just fine... And I've dropped it who knows how many times. It's chipped, the lip is cracked and one of the sockets that holds the arm in place is missing the bottom half but it still reads right every time. In 4 years it hasn't varied (checked against calibrated refractometers). There is no refractometer out there than can beat that.

lolz i think i got lucky on my hydrometer also. i think it got calibrated really good. cuz i check mine with my lfs refractometer and and precicely accurate. mines pretty beat up also

[Mr. Microscope]

Still looking for a table or calculator for mixing up water to SG. I think I figured that approximately 0.032g/mL = SG 1.023 and 0.04g/mL = 1.025. How does the curve work here?

[Mr. Fosi]

It is dependent upon the salt you're using.... the volume of the salt would change over time as it adsorbed water, but that was fine.

 

Mass will change also.

[youincolor]

I remember seeing your posting last week of some hitchhikers on your rock, which leads me to believe that you haven't added any livestock yet. Going by that knowledge, I'm going to agree with every third person here and say just top off with salt water for a while, check with hydrometer, and stop when you reach desired level. It doesn't need to be so scientific, nothing is going to die at 1.021.

[Hawaii_Bio_Cube]

Will most LFS calibrate your refractometer for you?

[Mr. Fosi]

Dunno. Not sure if I'd trust them to do it anyway.