Reef Discussion

[potatocouch]

As I start reviewing my equipment, I noticed that I haven't been investing much in my Refractometer.

I have 2 refractometers, on both occassions, I bought them from eBay (China), so quality is questionable.

I talked to my LFS and he said there is no need to purchase to expensive Milwaukee or Hanna branded one ... just come in and he'll calibrate it for me.

In saying that, I don't think my one is calibrate-able ... so the story is (from day 1 since I got it):

• Used RODI water and calibrate it to 0 SG.
• The next day, when I used RODI water and I'm expecting 0 SG, it goes off 0 SG ...
• So, I calibrate it again to 0 SG.
• The next day, it went off again ... ... like WTH ...

This is the one with knot .. not the screw.

Is this one doomed? no good? what/which one should I purchase? If I fork out $$$ for good ATC refractometer, it doesn't guarantee that I'm not getting a bad batch, am i?

 

[NiCd]

Have you tested it against the NSW you collect?

All that really matters is that it matches up to that, if it says your local NSW is 1.030 try and maintain that, using the same one.

Mine reads RO water as 1.00 but my NSW as 1.031 but its actually 1.026 according to a hanna as well as what you would expect it to be. So don't take a 1.00 calibration as being linearly correct, the only correct datum you need to worry about it the one where you want your water to be.

 

[IJG3145]

..

 

[Savage Henry]

Have you tested it against the NSW you collect?

All that really matters is that it matches up to that, if it says your local NSW is 1.030 try and maintain that, using the same one.

Mine reads RO water as 1.00 but my NSW as 1.031 but its actually 1.026 according to a hanna as well as what you would expect it to be. So don't take a 1.00 calibration as being linearly correct, the only correct datum you need to worry about it the one where you want your water to be.

Where does your NSW come from? This is good info for me for other reasons.

I follow exactly this: have always had my refractometer read 1.029 for my NSW and I just keep an eye on my tank to ensure that it hasn't varied much from 1.029. Because I use tank lids, I do not have to replace water and my salinity does not vary much at all.

 

[Savage Henry]

As I start reviewing my equipment, I noticed that I haven't been investing much in my Refractometer.

I have 2 refractometers, on both occassions, I bought them from eBay (China), so quality is questionable.

I talked to my LFS and he said there is no need to purchase to expensive Milwaukee or Hanna branded one ... just come in and he'll calibrate it for me.

In saying that, I don't think my one is calibrate-able ... so the story is (from day 1 since I got it):

• Used RODI water and calibrate it to 0 SG.
• The next day, when I used RODI water and I'm expecting 0 SG, it goes off 0 SG ...
• So, I calibrate it again to 0 SG.
• The next day, it went off again ... ... like WTH ...

This is the one with knot .. not the screw.

Is this one doomed? no good? what/which one should I purchase? If I fork out $$$ for good ATC refractometer, it doesn't guarantee that I'm not getting a bad batch, am i?

View attachment 52892

I was drilled a little bit about this on another forum.

Best thing you can do is maintain salinity as suggested NiCd or you could find a standard solution at the salinity you desire and calibrate your refractometer to suit.

However, I think that what you are really asking is whether your refractometer is really working at all. They are suppose to have some variation due to temperature etc. Mine is suppose to be an automatic one that doesn't require adjustment so I don't worry about that.

Best advice I can suggest is do this test on the same day within about one hour duration: test with RODI ten times. Then test with your NSW ten times. Then test with RODI ten times. This should give you an idea about the precision of your instrument. Get back to us if it is varying.

You might find that if its a crappy refractometer it might have to be calibrated every time you use it. If this is the case then I would definitely get hold of a standard solution near the salinity you want and use it to calibrate before testing your NSW.

 

[NiCd]

I collect mine from Lilli pilli boat ramp

 

[Savage Henry]

Beautiful spot to collect.

 

[NiCd]

Beautiful spot to collect.

Ive been going there 21 years now, im not sure if its more out of habit, actually having good water or that its one of the easier spots to collect from

 

[Savage Henry]

I guess it would be better if it were closer to the entrance to Port Hacking, but I know you get a strong current coming past there on an incoming tide so it shouldn't be too bad.

It's my favourite area to fish out of my kayak.

There's some huge squid off there at night.

 

[NiCd]

I have not gone fishing in years but it used to be one of my favorite spots, its the only place I have caught a spanish mac further south that port macquarie and also the only time not on a boat in open water. You seemed to get a mix of everything there.

 

[Savage Henry]

Yeah, all sorts of things turn up there. You've probably got coral beauties and bicolour angels at your feet in summer.

 

[NiCd]

I got into the hobby through my uncles who used to collect their own out at boat harbour, they had 14' FOWLR tanks with hundreds of fish in them.

I had a 4 footer with all manner of wrasses, triggers, damsels, butterflies and angels (well and truly overstocked with very unsuitable species) and all of it was collected locally at the end of summer.

From what i gather it was all legal back then in the respect of it wasnt illegal, not sure on the status now?

 

[Savage Henry]

Our summer visitors have begun to arrive. I got bitten by a sabre tooth blenny last week. The little bugger probably thought it had come across a dugong from up north.

 

[NiCd]

From what I am told they all die down here once the water changes temp, from a sustainable collection point of view you think there would be something ecouraging collection down here to save what is up there?

 

[Savage Henry]

Yep, always toward the end of their "visit" down here I see less and less of them and usually near the end I see specimens that are not in the best condition at all.

Funny thing is I always see the same fish in the same spots year after year and they are usually of the same size. For example, I see at one spot a cleaner wrasse. It is there year after year. Presumably it is not the same fish, but one always turns up and takes its place there. Same goes with a dragonette.

 

[ezza]

I saw one of these Ocellate Damselfish at Copacabana a week or so back. I was flabbergasted!

 

[NiCd]

I still giggle each time I see you avatar ezza

 

[Savage Henry]

View attachment 52902

I saw one of these Ocellate Damselfish at Copacabana a week or so back. I was flabbergasted!

I've seen that one many times and caught one for photographs. Didn't see any last summer though.

I always see a few Neon Damselfish (Pomacentrus Coelestis) and I saw a single Threespot Dascyllus (Dascyllus Trimaculatus) about two years ago.

Still waiting to see my first angelfish in Sydney.

 

[potatocouch]

I've been wanting to ask this ... is there anything as fake refractometer or just a bad one?

I noticed some are twist and some are screwdriver ... which one do you have? why?

 

[Savage Henry]

I have a Sybon Refractometer.

It has the screw adjustment.

I only have it because a fellow reefer sold it to me when I bought some corals from him several years ago. I don't know where it is made, but it appears to be a quality one.

It gives consistent reading for me: time and time again I have tested my NSW and it always gives the same reading. I set it to 0 with distilled water and get a measurement of 1.029 with NSW. I don't care if the NSW is actually 1.026 or 1.030 because I'm not going to do anything to it, but use it straight as is.

If yours is a cheaply made one, then it might not only not be accurate, but also it might not have any precision.

It's just a matter of testing it with your NSW. As I wrote above, test it say ten times within an hour and see how the results vary. Good to test it ten times with say NSW, then ten times with say tap water or RODI (vinegar if you want), then with NSW and see how it performs.

You want precision, that is, test it ten times and it gives the same result. Accuracy is not that important if you have a set point from a consistent standard (like RODI) you want to obtain and remain at.