SG Measurement

[Geecee]

Well this is confusing - When I set up my reef tank I bought a small floating type hydrometer with thermometer, this I have used for the last 17 weeks or so. lately been reading about how inaccurate these areso I purchased a swing arm type - results are:-

Floater 1024
Swing 1021

Hmmmm took a sample to LFS and asked him to check on his refractometer - guess what 1025/1026

Pretty wild and differing results methinks and yet I just read an article saying nearly all swing arm types tested were pretty accurate.

I tried dipping my finger in the tank and tasting it - yep definitely salty :D

So which do I believe?

Geecee

[SteveS]

i'd lay money on the refractometer being spot on, swing arms and hydrometers can differ slightly, but if your sg is low/high its stability thats the key rather than a low/high sg, obviously not too low/high :) if you lower/raise it do it very slowly over a period of days/weeks

hth
steve

[Geecee]

thanks Steve - think I lean towards the refractometer also - bit of a wake up though when you rely on these bits of kit.

Geecee

[Electric Monk]

Agreed, refractometer is the way to go. Swing arms are pretty bad by design

As for the finger test....

[Geecee]

Why does everything always taste salty?:D

There is an article I think in Practical Fishkeeping where 2 guys seperately tested the swing arm types and came to the conclusion that they were accurate within the bounds of acceptability hence me buying one. I cant vouch as I only have the one but I should think the refractometer would be the most accurate

Geecee

[MR Teee]

They also tested a load for a recent issue of reefkeeping.com.

That if use correctly they all gave similar results to a refractometer.

TBH though, I have used them and found them to be inaccurate. I prefer the ease of use of a refractometer.

[Geecee]

S'pose I got to persuade the missus I need a refractometer now.

Geecee

[brian waller]

Why does everything always taste salty?:D

There is an article I think in Practical Fishkeeping where 2 guys seperately tested the swing arm types and came to the conclusion that they were accurate within the bounds of acceptability hence me buying one. I cant vouch as I only have the one but I should think the refractometer would be the most accurate

Geecee


hi geecee,you must keep the swing arm type spotlessly clean, rinse in white vinegar and hot water every time you use it,or they stiffen up.


brian.

[Geecee]

Thanks Brian

This is brand new but I have rinsed in RO water every time I have used it.

Geecee

[brian waller]

Thanks Brian

This is brand new but I have rinsed in RO water every time I have used it.

Geecee



hi geecee,ro water on its own is no good, it has to be quite hot with white vinegar to shift the salt that you cannot see.


brian.

[Geecee]

Well I made a decision to give up with the swing arm and floaty types. I am away abroad for work for the next two weeks but will buy a refractometer when I return.

Geecee

[MR Teee]

I would get the Deltec or Aquamedic. Some of the non branded ones are made for measuring alcolhol or honey?! and have the wrong scales on them.

[Chris, Reef Ranch]

They are all incredibly inaccurate. Use a Deltec Refractometer to regulate to natural levels. 35PPT or 3.5% (35g/litre). We have one in stock. The aqua medic ones are the same piece of kit but £10 more expensive.

Chris