Specific Gravity ?

hdross

hdross

New Member
I bought a 75 gal reef tank yesterday. The fellow I bought it from was using a hydrometer to measure his SG. Said it was 1.024. When I got everything set up I measured with a refractometer and reads 1.012. My question is how should I raise the SG to 1.024? How guickly should I raise it.
 
spanko

spanko

Active Member
If there is livestock just do topoffs with premixed saltwater of the Sg you want to attain. If no livestock do topoffs with premixed saltwater with an Sg of 1.027 of so until you get to your desired level.
JMO
 
meowzer

meowzer

Moderator
Hi everybodeeeeee....LOL....If you just bought it yesterday, How did you move it? Just out of curiosity...did everything get stirred up?
 
hdross

hdross

New Member
Bought it yesterday and nearly killed me moving it. 165 lb. live rock. 2 lg. clams, yellow tang, 3 percula, hipo tang, and flame hawk. Numerous corals, open brain, frog span, lots of zenia, mushrooms, crabs and snails, a couple of shrimp. Everything is doing well. The tank is clear, We put most of the water in a new trash can, anf filled salt buckets with h2o and rock and corals. When we put the h2o back in the tank we used a small submersible pump and verv carefully returned the h2o to the tank. The SG was only 1.012. I need to get it up to 1.024. I got the refugium, and all equipment.
 
meowzer

meowzer

Moderator
Originally Posted by hdross
http:///forum/post/3046252
Bought it yesterday and nearly killed me moving it. 165 lb. live rock. 2 lg. clams, yellow tang, 3 percula, hipo tang, and flame hawk. Numerous corals, open brain, frog span, lots of zenia, mushrooms, crabs and snails, a couple of shrimp. Everything is doing well. The tank is clear, We put most of the water in a new trash can, anf filled salt buckets with h2o and rock and corals. When we put the h2o back in the tank we used a small submersible pump and verv carefully returned the h2o to the tank. The SG was only 1.012. I need to get it up to 1.024. I got the refugium, and all equipment.
That's how they moved my 54g.....and what little bit got stirred up...it settled within a few hours....
HEY HOW ABOUT SOME PICS....
 
ophiura

ophiura

Active Member
YOu need to get an LFS to verify the specific gravity reading. Did you calibrate the refractometer with distilled water? It is a stupid question, but it is a refractometer for this use, right? There are many types of refractometers and many are not for saltwater.
If it was 1.012 all of the invertebrates would be dead, I guarantee it. If you assume it is low, you can easily kill things as well. You need to take a water sample immediately to an LFS and have everything checked. Odds are there is a high risk of an ammonia spike.
 
hdross

hdross

New Member
The refractometer has been calibrated, and is the correct one. I am ready to do water changes in case of amonia spikes. I was just wondering how gradually i need to raise the SG. This tank had been set up for four years.
 
ophiura

ophiura

Active Member
If you moved all of the water, and didn't add any more, then there is an issue somewhere. Hydrometers can be off easily by .002, .003...but being off by .01 is not common. Believe me, the inverts would not be looking good if the specific gravity were actually 1.012, which is basically brackish water.
Levels below 1.024 become quite stressful for most marine invertebrates, which is why low specific gravity is used as a parasite treatment for marine fish. The inverts would be a signal something was wrong if that 1.012 is accurate.
In general specific gravity should be brought up very slowly, over days, as sudden fluctuations are very stressful. But if it gets too high it is also an issue.
All I am telling you is that, as an invertebrate zoologist, I think there is an issue with the 1.012 reading. Perhaps not, but I would be very surprised if he ran a thriving reef tank at that specific gravity. It would be just about unheard of...so something is not adding up.
A reading of 1.021 I could believe, and this should be brought up slowly over several days by adding salt water as top off water.
 
hdross

hdross

New Member
Re checked the SG again and it is 1.016. I dont know if i looked at it wrong the first time or just had a brain f--t. I have re checked the refractometer and it is calibrated. It is a very good refractometer so I believe the reading. Should I just start adding a higher SP H2o a little at a time?
 
ophiura

ophiura

Active Member
Personally I would get a second reading from the LFS. Anything below 1.024 would be a stress on corals and such, so I would expect them to not be extended, acting normal, etc. Do you have a picture?
Though relatively less stressful, going too high on specific gravity is also not good, so I would not just add salt.
How about this...
Make a gallon of water according to the manufacturers direction, which should place it at 1.021 or something. Test this water and see what it reads.
 
hdross

hdross

New Member
Well now I am really confused. I took my H20 to be tested. It was 1.025. How do you tell the difference between refractometers. Mine was 125.00 and is supose to be for Salt H20. I calibrated it with distilled H20. I did notice while reading under SPG it said urine. It is a total solid meter.
 
ophiura

ophiura

Active Member
I am afraid you may have the wrong type of refractometer. It is likely a clinical refractometer. How many scales are on it when you look through the eyepiece?
 
spanko

spanko

Active Member
Originally Posted by ophiura
http:///forum/post/3046451
I am afraid you may have the wrong type of refractometer. It is likely a clinical refractometer. How many scales are on it when you look through the eyepiece?
+1, wrong type. The one I have only has two scales on it.
 
ophiura

ophiura

Active Member
So the good news is your tank is ok :) and you won't be losing a bunch of inverts immediately...
Just the wrong kind of refractometer it appears.
 
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