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HELP. Salinity dropping

SomethingFishy

SomethingFishy

Okay some I'm new to reefing and maybe I'm doing something wrong or I am watching all my levels too much. Last few days my SG keeps getting low. For example today it was 1.023 and I want it to be 1.025.
I have a 32 gallon biocube and did a 5 gallon water change.
I mixed a bucket of 1.026 and now my tank has gotten lower 1.021.

Can salt precipitate?
I recently switch from instant ocean to red sea, would that cause problems?

Advice, comments, ideas all welcomed.

Thanks

SG- 1.021
Temp- 80F
PO- 0
NO3- >1
CA- 480
dKH- 11

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SomethingFishy

SomethingFishy

Normally yes, but all week SG has been low...so every 1-2 days I have just been doing water changes to try and get back to 1.025. Seems like I'm just going in circles because it just keeps dropping

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SomethingFishy

SomethingFishy

No dosing, just weekly water changes. Only 2 things I've done differently is change brands of salt and calibrate my refractometer. I am starting to suspect the refractometer. I used 35ppt solution and even tried RO water to see the difference but both calibrate it to the same readings for RO or 35ppt.

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SomethingFishy

SomethingFishy

After skimming the internet for a bit, it seems the red sea refractometer may just be a piece of junk and my tank may be fine. I think I will be stopping at my LFS to complain about this $60 paperweight they sold me

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H

horseplay

NJRC Member
Refractometers are low tech equipment and it's pretty hard to have a bad one. Make sure it's calibrated to 1.0264 and try to match that with your tank water. If you don't have calibration fluid just get a bottle of salt water from a fellow hobbyists. To increase salinity, add some salt water and wait for your tank to evaporate.
 
SomethingFishy

SomethingFishy

horseplay said:
Refractometers are low tech equipment and it's pretty hard to have a bad one. Make sure it's calibrated to 1.0264 and try to match that with your tank water. If you don't have calibration fluid just get a bottle of salt water from a fellow hobbyists. To increase salinity, add some salt water and wait for your tank to evaporate.
Click to expand...
I used 35ppt fluid to calibrate. I just checked with my hydrometer and it is reading 1.025 SG and refractometer is reading 1.021 SG. Doesn't make much sense for refractometer to be bad, but it also doesn't make sence for SG to just drop. I may have to buy another refractometer and check it vs the other and hydrometer.

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H

horseplay

NJRC Member
SomethingFishy said:
I used 35ppt fluid to calibrate. I just checked with my hydrometer and it is reading 1.025 SG and refractometer is reading 1.021 SG. Doesn't make much sense for refractometer to be bad, but it also doesn't make sence for SG to just drop. I may have to buy another refractometer and check it vs the other and hydrometer.

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Click to expand...

If you have calibrated then your tank water is not 35ppt. It is close to 1.021 SG. Why bring your hydrometer into this? And how do you know the hydrometer is accurate?
 
redfishbluefish

redfishbluefish

Officer Emeritus
Officer Emeritus
When you are measuring salinity of new water, is it heated up to tank temperature? If it's still cold, you'll see a higher salinity number compared to when you heat it up to tank temperature.
 
njtiger24 aquariums

njtiger24 aquariums

Officer Emeritus
Article Contributor
horseplay said:
If you have calibrated then your tank water is not 35ppt. It is close to 1.021 SG. Why bring your hydrometer into this? And how do you know the hydrometer is accurate?
Click to expand...

I agree with @horseplay here. I would trust the ref over the hydro. Hydros are very inaccurate and as you stated you used calibration solution on your ref.

redfishbluefish said:
When you are measuring salinity of new water, is it heated up to tank temperature? If it's still cold, you'll see a higher salinity number compared to when you heat it up to tank temperature.
Click to expand...

I also agree with @redfishbluefish . I normally don't check my new water until its already up to tank temp and been mixing for some time.

Also could you be topping off with too much water which is lowering your salinity? Are you using an ATO or doing it by hand?
 
SomethingFishy

SomethingFishy

njtiger24 aquariums said:
I agree with @horseplay here. I would trust the ref over the hydro. Hydros are very inaccurate and as you stated you used calibration solution on your ref.



I also agree with @redfishbluefish . I normally don't check my new water until its already up to tank temp and been mixing for some time.

Also could you be topping off with too much water which is lowering your salinity? Are you using an ATO or doing it by hand?
Click to expand...
No top offs this week. I always check SG before manually topping off. I also heat and run a power head in my mixing buckets until temp matches tank.
The refractometer is junk. I'm not sure why you guys trust it so much. Anything that has to be calibrated can break. I deal with bad tools all the time at work.
I used the refractometer and made several test last night.
It tested 1.021, 1.025, 1.024, and 1.022.
That makes me certain this red sea refractometer is erroneous and I am using my hydrometer for a second opinion. It constantly tested 1.024 and 1.025. So I will post what happens after I purchase the Milwaukee refractometer

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njtiger24 aquariums

njtiger24 aquariums

Officer Emeritus
Article Contributor
SomethingFishy said:
No top offs this week. I always check SG before manually topping off. I also heat and run a power head in my mixing buckets until temp matches tank.
The refractometer is junk. I'm not sure why you guys trust it so much. Anything that has to be calibrated can break. I deal with bad tools all the time at work.
I used the refractometer and made several test last night.
It tested 1.021, 1.025, 1.024, and 1.022.
That makes me certain this red sea refractometer is erroneous and I am using my hydrometer for a second opinion. It constantly tested 1.024 and 1.025. So I will post what happens after I purchase the Milwaukee refractometer

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Click to expand...

The reason most reefers dont trust the hydros is because unless you clean them externally well their arms don't flow as easily as it should given inaccurate readings. If your using calibration solution and your calibrate your ref to 35ppt then your ref should be accurate (unless you have a bad batch of calibration solution which can happen). Yes equipment can break, yes there can be junk ref. I just find it hard to believe if you calibrate your ref to 35ppt, test your water that reading to be off but I will admit I could be wrong.

Question when you are testing and getting the low salinity is that only on the ref, only of the hyrdo, or both reading low/dropping (even if their numbers are not the same)?

Hopefully the Milwaukee unit will help out.
 
redfishbluefish

redfishbluefish

Officer Emeritus
Officer Emeritus
Actually refractometers are very reliable pieces of equipment. However there are things that can give you erroneous results. Two that immediately came to mind are:

1. Consistant wavelength of light to read the refractometer. Different wavelenghts of light (different light sources) will give you different readings. It doesn't matter what light source you use to read your refractometer as long as it is consistent with the same light source used to calibrate it. I prefer using sunlight (daylight) to calibrate and read my refractometer.

2. Freely moving cover door. That multi hinged door that closes over the top of the refractometer needs to move with extreme ease. Over time salt finds its way into the hinge pins and starts to make the movement of the door more difficult (not fully resting on the glass plate.) If the door isn't resting the same way every time, you'll get an erroneous reading. What I do is to first squirt a very small amount of WD40 into a small glass (shot glass....I actually use an aperitif glass because of the conical bottom). Using a toothpick, dab the WD40 on the hinge pins while moving it back and forth. Repeat with all four hinge pins until that door falls shut with great ease on its own.

Hope this helps.
 
Last edited:
SomethingFishy

SomethingFishy

UPDATE, first off, thank you everyone for chiming in. Talking to you guys is gold, so thank you for bouncing ideas to me. At LFS, they have confirmed my refractometer is junk. (Red sea) they tried to calibrate it then tested their apex controlled tank and it was .004 off. Then used solution and test off again. I got my money back. Buying a Milwaukee refractometer. My SG on hydrometer is correct

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