Refractometer ?

[Snailman]

I purchased one from FishWish several months ago and I love it. I have noticed one strange thing that I do not understand. I check my salinity everyday on my 400 gallon tank and add RO/DI water if necessary. I try to hold my salinity right around 1.025. I have noticed that the water level keeps going up in my tenk. :confused: So once a week or so I have to take some water out of the tank so that it does not get to high. What is going on here?

[Larry M]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Snailman:
:confused: So once a week or so I have to take some water out of the tank so that it does not get to high. What is going on here?<HR></BLOCKQUOTE>

Snailman--I'm a little confused by what you're saying here. The salinity keeps going up? Or the water level???



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Larry M

"My Dad could build--or fix--anything. Just give him a hammer, a saw, a piece of wire, and a stick. Then get the hell out of the way."
In response to the question, "Where did you learn how to do that?"

See my tanks at Northern Reef (http://www.reefcentral.com/northernreef/index.htm)

[Doug]

Hi Snailman,

Like Larry said let us know a little more about what you are looking for.

I will take a stab at it though.

If you are saying that your water level in you tank is rising could your overflows be dirty? I notice on my 75g that when my U-tube overflow gets dirty the water level in the tank rises and the sump level is lower. Also if the teeth on top of the overflow get full of algae the water level will go up.

HTH

Doug

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Doug's Reef and Fish Page (http://38.222.244.200/dougw)

[Snailman]

Sorry that I was not clear. My tank is a 4'x7'x'2 box that sits on the floor. It has four 1" double headed U tubes that siphon water into a 40 gallon Sterlite tub that then feeds the pump. The pump feeds a CC skimmer and a 20 gallon surge device. Because of the tank design you can raise and lower the water and the U tubes just keep getting it, unlike an overflow corner box. I wanted to drill the wall of this tank but my wife said no way and she got a good reefer friend of ours to agree with her. :(

What happens is this. I check the water and it reads 1.026. I put RO/DI water in. Tomorrow I come back and check it again and if it is above 1.025 I put water in it again. This goes on day after day. I notice that that water level is up after a week of this. :confused:

[Anemone]

Okay, so your question is why do you have to raise the water level in your tank to keep the specific gravity the same? Do you use any other additives?

Kevin

[Frisco]

It sounds like you are just seeing an artifact of your supplementation or feeding regimen. Don't forget that you are measuring the index of refraction of the fluid - which can be correlated to SG and salinity - and not either parameter directly. So DOC, bacterial counts, suspended sediments, etc can all contribute to skew the results. While this might sound like a limitation of the measurement, it could also skew the results of a buoyancy or conductivity measurement.

If you're using a reactor, there's about a 100:1 ratio of the calcium output to the next most concentrated element (Mg I think) so it doesn't seem likely that would be the cause... I mean, say you're sucking up 100 ppm of Ca every day and that means you're putting say 1-7 ppm of other atoms (combined) that aren't consumed proportionately... you'd still only have about 10-50 ppm building up... not ppt concentrations... My gut instinct is that it's the organics or food decomposition that's affecting the results.

[Larry M]

Either that or someone is dumping salt in when you're not looking. :D
Sorry, I couldn't resist.
I don't know Jon, usually the opposite happens as skimmers do their job, etc. But I would think Frisco is probably on track. It seems like it is quite a jump, though, in one week. Like someone else asked, are you using any other additives? B-Ionic will raise salinity a bit.

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Larry M

"My Dad could build--or fix--anything. Just give him a hammer, a saw, a piece of wire, and a stick. Then get the hell out of the way."
In response to the question, "Where did you learn how to do that?"

See my tanks at Northern Reef (http://www.reefcentral.com/northernreef/index.htm)

[npaden]

I have read that using liquid calcium will raise salinity due to some chemical stuff that I don't understand. My personal experience is opposite. As I go down the road from a water change I add top off water to the sump to keep everything the same volume. Over the month between water changes my specific gravity will go from down around .001 before my next water change so use slightly saltier water on the water change to bring it back to where I want it.
FWIW, Nathan

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Visit my homepage at padens.homepage.com (http://padens.homepage.com)

[Snailman]

Thanks for all of the ideas. I think that Frisco may be on it also. The tank has about 30 damsels and three large (6" - 8") engineer gobies. The gobies get fed tablet food once a day and the damsels get fed flake food two to three times a day. The only other thing that goes into the tank is Kent Turbo Calcium and Kent SuperbufferDKH. I am putting the finishing touches on my big DIY dual cahmber calcium reactor so that dosing will end soon. Because this tank is not glass you only look through 2' of water to the bottom of the tank so you don't see any color in the water. I went to Julian Sprung's discussion at That Pet Place's tent sale back in the spring. He said to take two white buckets and put some RO/DI water in one and some tank water in the other one and compare. I came home and did it and I was shocked. I feed a lot and I also has a huge crop of Caulerpa prolifera, but I did not expect to see the water as BRIGHT YELLOW as it was :eek: I must admit that I am not a big water changer and I have never run any carbon. I got some and ran it and the water cleared right up. :) My Caulperpa grows real good and the 6' CC skimmer also does a good business.

So... knowing all of this, how do I find the salinity of the water?

[Frisco]

You need a mass spectrometer! that's the best way I know of to get a feel for the atomic makeup of something... but it's really not the kind of thing that's appropriate for a meager budget... the last time I checked a new MS was somewhere around 100K... keep the limitations in mind, and if you're really concerned add a conductivity meter as a double check...

That white bucket test can be pretty alarming huh?

[Snailman]

Frisco that is a great idea. I used to work on MS years ago. :) I was a high vacuum tech. I kept those diffusion pumps humming. :D I will keep my eye out on ebay for one. :)

http://www.reefcentral.com/smilies/council.gif

500 I just noticed.



[This message has been edited by Snailman (edited 08-24-2000).]