In my attempt to do a hyposalinity treatment

[rbonafide]

I was trying to get my salt reading to 11 and I was at 12.5 last night and all of a sudden I awoke to a 6 reading..Somehow the fish are still alive, I have a 240 gallon main tank, 75 gallon sump and 50 g refugium. I quickly did a change and this time with salt (reef crystals) Should I be doing something else? I can add just straight saltwater without extracting water once my tub gets heated (it hold approx 50 gallons) HELP please I am so scared!!!

[Randy Holmes-Farley]

How are you measuring salinity?

11 means a specific gravity of 1.011? or 11 ppt?

[rbonafide]

1.011 I use a refractometer

[Yogre]

Sounds like you're hypo-ing your display tank. Do you have inverts or corals in your tank?

If so, they most likely won't take well to hypo. I'd advocate using hyposalinity treatment in a separate tank if you can.

[Chris27]

The fish are OK because you brought the salinity down, the last thing you want to do is raise it quickly. Before you make any drastic changes, ensure that your method of measuring (hydrometer, refractometer or probe) is calibrated, and continue on slowly from there.

[bertoni]

I would raise the SG over a half hour or so, by doing some water changes with normal-SG water.

[rbonafide]

Thanks guys, and yes it is a new display tank so I waited for inverts and corals etc. in case of something like this happening. I did raise the salt by a water change and did so before reading the responses (i was extremely nervous) Anyhow I got it back up to 12 actually and all fish seem very good except for 1 lyretale anthias (the male) Thanks for the input. I guess I will keep it this way for 5 days or so hoping to cure what I believe is ich. Although one moment it looks like they have it and then the next day it is barely there. Man this is tough.

[bertoni]

I think the usual recommended level for treating marine ich is about 1.009. I'd target that level. You might want to make a rough calibration guide by combining two parts of RO/DI water and one part of saltwater at 1.0264, since your refractometer or hydrometer might be inaccurate at that low a level.

[nuccadoc]

Thanks for that info bertoni. I am doing a hypo treatment on a tank right now and I was unsure of the salinity I needed to be at.

[Chris27]

5 days problably won't do it either, better to go at least 4 weeks around 1.009 - longer if you see some more white spots on your finned friends.

[jimmyj7090]

I would guess that your last dilution hadn't mixed in fully when you checked it last night. Once it thoroughly mixed you got the true, lower reading.

As others have already said, Hypo treatment is useless if you don't do it right. 1.009 max, and 4-6wks min. A higher SG, or shorter time will do nothing but slightly annoy the ick.

Also, IIRC it's best to calibrate your refractometer to 1.0000 solution and not a seawater level reference, when your testing at hypo levels.

[Dejavu]

Just remember that you can lower salinity pretty fast (over a few hours), but when raising it it needs to be done slowly (over a few days).

[rbonafide]

Thanks guys,
Yes today I will bring i back to .011 or hope to get in that range

[Randy Holmes-Farley]

Yes, I'd use RO/DI to calibrate the refractometer. It won't be perfect at that salinity (nor will a seawater standard), but RO/DI will be a bit closer to accurate, and it will be close enough.

[rbonafide]

Thanks Randy,
You mean just calibrate the refractometer with RO water? Also when you place Ro water on it do you then just adjust it to the bottom level/number?
Thanks so much guys

[jdak]

I am going through the same. Just bought a new refractometer. Seems to need calibrated about every use. I am keeping my salinity at 1.008 to 1.009.... just thinking at .011 might be high. I read don't let it go over 1.010 cause a few might survive. I have a stars and stripes puffer, tomato clown, and yellow tail damsel. No signs of stress over the last two weeks. Everything is good at the moment but like you said OP, one day its there, the next it's gone. Also, whats in your refugium? I took all LR out and had no inverts. Did you disconnect your refugium? If not, stuff might be dying and that will spike ammonia big time.

[Randy Holmes-Farley]

You mean just calibrate the refractometer with RO water? Also when you place Ro water on it do you then just adjust it to the bottom level/number?

Yea. Adjust it to read 1.00000.

[RBU1]

Originally Posted by Randy Holmes-Farley

Yes, I'd use RO/DI to calibrate the refractometer. It won't be perfect at that salinity (nor will a seawater standard), but RO/DI will be a bit closer to accurate, and it will be close enough.

For the record. I get a little difference calibrating with RO/DI versus pinpoint calibration fluid. With Ro/Di water I read about 2 points below 0 with the calibration fluid I am right on at 1.026

[jdak]

Originally Posted by RBU1

For the record. I get a little difference calibrating with RO/DI versus pinpoint calibration fluid. With Ro/Di water I read about 2 points below 0 with the calibration fluid I am right on at 1.026

So how does RO water have a negative amount of salt. Where do you get your calibration fluid from. Does it get the chance to evaporate at all? This would cause higher salinity. I believe RO water has no salt and is fine to calibrate with. If someone really wanted to be sure, get some distilled water.

[Randy Holmes-Farley]

FWIW, that is the expected result. It is not a consequence of negative salt or evaporation, but of trying to use a salt (NaCl) refractometer (as nearly all sold for the reef hobby actually are) to measure seawater salinity, which is a lot more complicated than simple NaCl.

It goes back to the fact that 35 ppt seawater will not read 35 ppt on such a perfectly calibrated salt refractometer. In fact, it reads about 1.7 ppt higher. We try to get around that by calibrating it to read 35 ppt in 35 ppt seawater, but then it will necessarily read a bit off in pure fresh water.

I discuss that in great detail in this article:

Refractometers and Salinity Measurement
http://reefkeeping.com/issues/2006-12/rhf/index.php

Specifically here:

Imperfect Refractometer Use: Scale Misunderstanding and Salt Refractometers
http://reefkeeping.com/issues/2006-12/rhf/index.php#14

[RBU1]

OK Randy so until I get a chance to read your articles what is a more accurate way to calibrate? Using RO/DI water and setting it to 0 or using the pinpoint calibration fluid and setting it to 1.026?

[tmz]

The internal salinity of marine fish is about 1.008.While they can adjust to higher sg by drinking and passing concentrated urine ; they have no ability to adjust to sg lower than their internal sg as water will diffuse into them . So 1.009 is the lowest you can go safely for any significant length of time. Raising sg should be done slowly in the neighborhood of .001/.002 per day. If treating the display with hypo I'd also watch ammonia closely as the treatment may suppress the biofilter at least short term.

[Randy Holmes-Farley]

OK Randy so until I get a chance to read your articles what is a more accurate way to calibrate? Using RO/DI water and setting it to 0 or using the pinpoint calibration fluid and setting it to 1.026?

It depends on whether the salinity you are measuring is closer to fresh water (like hypo is) or seawater (like in a reef tank). Use whatever you are closest to for calibration.

[RBU1]

Got it...

So............

if I am just using my refractometer to test my tank water I want to calibrate with the pinpoint solution.

If I am doing a Hypo treatment I want to use RO/DI water.

Thank You and I hope this helps the poster....

[Randy Holmes-Farley]

Happy Reefing.