Salinity Issues in Young 30 gallon tall tank.

[wickedpaul]

I started up a new 30 gallon tall tank which will eventually be a reef tank about two weeks ago. Buying items slowly to get everything I need without going broke all at once. Started the tank with 20 pounds of carribsea live sand, and 20 pounds of aragonite sand. Proper measures of Instant Ocean, and RO water. Currently running a hang on back skimmer, and two Koralia 1's for water flow.
My question is this. My salinity is way higher in the upper level of the tank than in the lower levels of the tank. What is going on?

 

[natclanwy]

What are you using to test your SG? Anything but a a conductivity probe or a refractometer will give you inconsistant and inaccurate results.

 

[wickedpaul]

I am using a hydrometer. People have been using them for decades, they work just fine. I am not talking about just a minor variance. I am talking that the tank water near the sand is right in the good range. The water at the top of the tank is off the scale for salinity.

 

[natclanwy]

Yes they do work fine if you aren't concerned about accuracy if you want to trust it its up to you, but I would bet that if you used a refractometer to test your water it would solve your problem.

 

[crypt keeper]

Originally Posted by WickedPaul
http:///forum/post/3058357
I am using a hydrometer. People have been using them for decades, they work just fine. I am not talking about just a minor variance. I am talking that the tank water near the sand is right in the good range. The water at the top of the tank is off the scale for salinity.

are you measuring with flow turned off?

 

[natclanwy]

It doesn't matter if he is testing with the flow on or off, if the water had truly stratified into different layers of salinity the readings would be just the opposite the higher salinity aka denser water would be at the bottom not the top. My guess is he is using a needle type hydrometer and there are air bubbles on the needle and when the hydrometer is sitting at the bottom of the tank the water pressure compresses the bubbles causing them to have less buoyancy than when they are at the surface.

 

[crypt keeper]

What are you talking about? I have placed my old hydrometer directly in my flow areas and have recieved a higher reading than when placed in calmer water. He is probably using the instant ocean one that everybody uses. You can base it off whatever you think. You can get as scientific with it as you want. The facts are he has a lower rating at the the bottom. Higher at the top. Most people have the highest flow at the top of a tank. This will mess with the reading on these crappy hydrometers.

 

[natclanwy]

and we are back to what I stated in the first place there is no issue with the salinity being higher or lower in the tank the issue is with the accuracy of the hydrometer. The needle type hydrometers are not designed to be used inside the tank in the first place and the flow in your tank will move the needle just as easily as air bubbles will. So scientific or not its just another problem with the accuracy of a hydrometer.

 

[sepulatian]

Originally Posted by natclanwy
http:///forum/post/3058549
It doesn't matter if he is testing with the flow on or off, if the water had truly stratified into different layers of salinity the readings would be just the opposite the higher salinity aka denser water would be at the bottom not the top. My guess is he is using a needle type hydrometer and there are air bubbles on the needle and when the hydrometer is sitting at the bottom of the tank the water pressure compresses the bubbles causing them to have less buoyancy than when they are at the surface.
I very much agree here. The denser water would be on the bottom, not the top. The hydrometer is inaccurate.

 

[wickedpaul]

Ok, well based on the bubble theory hypothesized within this thread. If I were to take the sample from the upper levels of the tank. Allow it to set in the hydrometer for say half an hour or so, the bubbles should go away and the reading should be correct.

 

[taznut]

Originally Posted by natclanwy
http:///forum/post/3058549
It doesn't matter if he is testing with the flow on or off, if the water had truly stratified into different layers of salinity the readings would be just the opposite the higher salinity aka denser water would be at the bottom not the top. My guess is he is using a needle type hydrometer and there are air bubbles on the needle and when the hydrometer is sitting at the bottom of the tank the water pressure compresses the bubbles causing them to have less buoyancy than when they are at the surface.
+1

 

[natclanwy]

Originally Posted by WickedPaul
http:///forum/post/3058837
Ok, well based on the bubble theory hypothesized within this thread. If I were to take the sample from the upper levels of the tank. Allow it to set in the hydrometer for say half an hour or so, the bubbles should go away and the reading should be correct.
I doubt that the bubbles will go away on their own, when I used to use this type of hydrometer I used a pen to tap the swing arm and knock the bubbles loose. It allowed me to g et better results but they were still by no means accurate or consistently reproducible, I could take six samples and get six different readings and none of them would be right.
If you are keeping a fish only tank a hydrometer might cut it, but if you are keeping invertebrates or coral you would be better off investing in a refractometer. The inaccuracy and inconsistent results associated with hydrometers will only add to the difficulty in keeping these organisms. Not to mention it takes me all of about 3 seconds to accurately check the SG of my tank, I probably cut an hour of time off of my maintenance schedule each week just by switching to a refractometer.

 

[locoyo386]

Originally Posted by WickedPaul
http:///forum/post/3058220
I started up a new 30 gallon tall tank which will eventually be a reef tank about two weeks ago. Buying items slowly to get everything I need without going broke all at once. Started the tank with 20 pounds of carribsea live sand, and 20 pounds of aragonite sand. Proper measures of Instant Ocean, and RO water. Currently running a hang on back skimmer, and two Koralia 1's for water flow.
My question is this. My salinity is way higher in the upper level of the tank than in the lower levels of the tank. What is going on?
Hi there,
I do believe that if you see different levels of salinity it would be the other way around and I would only expect 0.2% varience on a 30" deep tank. With the flow you have, I really would not expect a significant differecne. On the other hand if you are indeed seeing a "way higher" (plese define this term with actual values), than they might be something in the water that it is not allowing the sand to mix well at the bottom. Some sort of oily media perhaps.