The Puffer Forum

Does anyone have a overview of the salinity a GSP needs at different ages, or rather different sizes (I have no idea how old my GSP is)?

I must have been really tired last night. I looked at that article, and didn't see the part about salinity

But thanks for making me look one more time I found my answer there. Now I just have to translate '' to cm But that I know where to find

And can you really trust those floating things to measure the salinity? It doesn't seem to change ever.
Maybe I should use that nice little thing in my avatar instead. She loves to drink that awful BW
She puts her nice little pink tongue through the feeding hole and drinks! She does this every time I forget to cover that little feeding hole.
I hope the puffer bites her tongue some time

Troender wrote:And can you really trust those floating things to measure the salinity? It doesn't seem to change ever.
Maybe I should use that nice little thing in my avatar instead. She loves to drink that awful BW
She puts her nice little pink tongue through the feeding hole and drinks! She does this every time I forget to cover that little feeding hole.
I hope the puffer bites her tongue some time

There is a debate on hydrometers and refractometers on accuracy, I have never used a hydrometer so cant comment on them but when I set up my brackish tank I puchased a refractometer from ebay and have found that really easy to use. Others use hydrometers with no problems.

Neale Monks says hydrometers are pretty accurate as long as they are properly used and cared for. For example, too many people use the floating hydrometers by sticking them into the tank when they actually need to be used in a container such as a drinking glass.

Ooops! That was new to me. I've used it in the tank. What difference does it make to use it in a glass? Except that the water stays more still?

I can still use my dog. When she stops drinking, I've reached fully SW

Any tool can be used, or abused, often without realizing the difference.

Floating hydrometers commonly are not calibrated for tank temperatures, and thus read erroneously if not corrected for temp. They are temperature-critical, that cannot be ignored. They are also motion/current sensitive, thus the requirement for a glass cylinder for readin accurately. Meniscus reading is a art in itself, and misreading is again a source of error. Cleanliness is equally important - anything coating the surface changes either the density or the reading or both.

The inexpensive swing arm hydrometers are accurate enough IMHO for most tank work (especially BW), but not for reef work. They are less temp-sensitive than floating glass hydrometers, largely because they are less sensitive and are intended for tank use and temps. They are however equally sensitive to being dirty - if not rinsed well in tap water after use, dried minerals or tank slime/proteins etc. can dry on the arm and give false readins, ditto trapped bubbles on the arm distort readings.

Refgractometers are far more accurate, but there is a learning curve to using them, as there is with the other techniques.

If you can't or don't follow directions well, you may be wasting your time. But then, there are a lot of tank techniques where that applies. If you use them properly, any of the techniques can do the job.

RTR wrote:Floating hydrometers commonly are not calibrated for tank temperatures, and thus read erroneously if not corrected for temp. They are temperature-critical, that cannot be ignored.

That is something I didn't know. That thing didn't come with a manual (neither did the first I bought, which my dog broke).
Do you know how much I have to correct the readings at tank temperature?

They are also motion/current sensitive, thus the requirement for a glass cylinder for reading accurately.

That should go without saying. It's virtually impossible to read that thing if it's not standing still. But it is possible to make that thing stay still in the tank. And I am aware that it must not touch anything.

Meniscus reading is a art in itself, and misreading is again a source of error. Cleanliness is equally important - anything coating the surface changes either the density or the reading or both.

I aware of that. That's simple logic. Anything attached to the hydrometer will change its weight, no matter how small. It's a fine balance in that thing.

The inexpensive swing arm hydrometers are accurate enough IMHO for most tank work (especially BW), but not for reef work.

I haven't seen those for sale at all in Norway. Maybe I just haven't known what they are for, and haven't payed attention to it, but I can't say I have ever seen one. Actually I haven't seen any hydrometer in any LFS either, not in this area, at least. I had to buy mine at a shop on the Internet. Actually the two LFS in my town, rarely have what I am looking for. And their knowledge is even worse. I wanted to bang my head into the desk, when one of them had never heard about a powerhead or a pump for circulating the water (and of course didn't sell them either - the other shop had one, but far too small for my use).

I found refractometers much easier to calibrate and use. And I'm not very smart, so if I can figure it out, anyone can.

Most floating hydrometers are calibrated for reading at 21C (69.8F). If they are quality instruments, they should include one of those impossibly tiny print papers with the correction curves or tables. And Troender, yes, exactly - fine balance is precisely what they do.

Boxermon - I have not tried lately, but I am not sure that I could read a refractometer any more. When I tried at the worst of my vison problems, I could not, but I have improved a bit since then. Reading the TDS is hard enough.