The Puffer Forum

Okay, so I've been ambling along, doing my brackish tanks in my own way -- not using any method to measure my salinity. I have decided that I might like to buy a hydrometer (just don't want to invest in a refractometer yet, as I only have brackish tanks).

I've noticed that most of them say they are for salt water usage, so I'm wondering .... what is the very lowest brackish measurement that I should be looking for on a hydrometer, as I think different ones have different scales. I think one I was looking at started at 1.010 ... which seems high to me, or am I wrong here? I'm just curious what salinity I do have my tanks at now, having done things my way. I've not crashed any of my tanks, and my fish seem fine, but for some reason, I have a feeling that my brackish water is weak, and I guess that's why I want to measure it.

I read some of the articles on mixing brackish water .... but I almost feel lost after doing it in my own way for so long. I blame my mentor who doesn't believe in measuring salinity!

This is what you need I believe: http://www.drsfostersmith.com/product/p ... catid=4952

It starts at 1.000

StormySkiez wrote:This is what you need I believe: http://www.drsfostersmith.com/product/p ... catid=4952

It starts at 1.000

Aye, that's what I've got, does the job and doesn't cost the earth!

Don't forget about the DFS rebates, guys!

That is a brilliant swing needle hydrometer. Just a small tip if you get one. I find it works best if you take the reading of your water twice, the second time you take it will be spot on acurate. I do this as different tanks are at different levles of salanity, and you want to make sure you rinse out any salt deposits from previous testing.

schismy007 wrote:Okay, so I've been ambling along, doing my brackish tanks in my own way -- not using any method to measure my salinity. I have decided that I might like to buy a hydrometer (just don't want to invest in a refractometer yet, as I only have brackish tanks).

First, good for you getting something to measure salinity.

Second, aren't refractometers supposed to be easier to deal with? With as many tanks as you have, it might be better to dish out the extra money and make your life easier.

Yeah but only 5 of my tanks are brackish, and I'm about to rehome my GSP's so that will make it only 4 tanks that are brackish .... so I can't see getting a refractometer just yet. I mean, I used nothing for all this time, so moving up to a hydrometer is good enough for now.

I have one of those floaty ones, cheaper, I don't know if their better. I guess you'd want to have one that starts at 1.000 and if your LFS doesn't sell one that does (like mine) go on ebay or the site the others gave you

I've actually found one on eBay, already ordered it. So just a matter of it arriving now.

Hi schismy007,

I've got a little swing arm type but stopped using that pretty early on when I did start keeping marines. I found the readings were not that repeatable because the arm on mine kept getting stuck slightly - enough for me not to trust the reading half the time. I did use the floating type but after breaking two at the join between the bulb and the stem, bought a refractometer on the princliple that it would be tougher. Just for me, I find they are easier to use besides not needing to be used at a certain temperature. Or correcting for temp, which you can.

I think the floating and swing arms need to be used at 25C, they're calibrated for that but I'm not sure what, say for example, a 3C difference would make to the salinity reading. I have seen conversion tables about for this and I'll try to find one to post for you. Or links.

BTW you can break refractometers, too! I dropped mine in a barrel of salt mix and it was the devils owns job to dissasemble, clean and recalibrate without getting either salt or grease on the prizm and lens. Recalibration involves moving a mirror back and fourth with tiny screws until you have a good image and testing with distilled water and salt solutions of weighed out concentrations until you think you trust it again. For the time, I'd probably have bought a new one!

Ahhh, FUN!

There's also not much wrong with weighing out salt to a known volume of water. So I don't think your's is a silly Q. If not for any other reason, I like to check tank salinity to check for evap losses. Just belt and braces - by weighing, you know what it should be. By using a device like these, you measure the actual salinity.

Also, the salinity you get seems to change for a given weight of salt and volume of water depending on the brand of salt. One brand I have used, seems to give less than I would expect.

Then there is water absorbtion, by salt. Not a massive problem, but given a chance, salt in a bag or bucket will pick up whatever water it can from the air if nowhere else but you'd have to leave something open to damp for weeks to really have a problem. It forms hard clumps and leaks seawater, eventualy, if you have not seen it this way. But I've also used salt that looks fine but I get less salinity for the weight than I should or as written on the box.

One last thing, I've found with one brand of salt, different from the last brand was that I get a massive nitrite reading in my mixing tank if I leave it mixing for three days onward. Sometimes, I think that's due to bits of seaweed I can see in it as it dissolves. Up to two days mixing seems fine and 24 hrs mixing and aeration seems to be recomended.

Just passing on what I've found with mixing salt (snore)!

Hi soggy ... thanks for that.

I actually received mine today, I only ordered it yesterday!! That was the fastest ever! Since I never used to measure anything, I thought I should start with something inexpensive, as I looked at the refractometers and it seems they are about £30 or so .... not prepared to pay that yet. I only have the 5 brackish tanks, and to be honest, I don't really need to test my 2 mudskipper tanks because they both use so little water that it's easy to mix up brackish water for them. So I only really need it for my Ceylon tank, and my 2 GSP tanks (I hope to be rehoming 3 of my GSP's next week, so that will leave only 1 GSP tank afterwards).

I have a question though -- once the bacteria in a filter adjusts to brackish water, do you still have to be careful about how much salt you add to that tank. In other words, if I add too much salt to a tank that has a filter that's adjusted to salted water, can I still crash it?

It seems I've done relatively well with my smaller tanks, but I've not got a very high salt content in my big Ceylon tank, and I now know I need to add more salt, but I don't want to crash my filters.

Hi there - 007!

I've not kept a brackish tank before. Only fw (from Malawi's to Chocolate Gourami's, once) and full marine in the last 3yrs.

It would appear so, yes: go slowly!

I can only point you to the info here that states you should only up the salt level by 0.001 to 0.002 s.g. per week to keep the bacteria you have alive or manage the change between fw and sw bacteria because they are different.

It's just the bacteria that's the prob, possibly. The gsp should have not that much of a prob with a sal jump so long as it was dripped into a big container over several hours.

What's your s.g. at the mo?

I'm just setting up for the T. fluvilatus, if you were not keeping your last baby - I'd be tempted to offer it a home also. Mbu's are out for now but give me time...!

I'm sure if you up the sal gently, things will be fine

And you have mudskippers - jammy individual!!!

BTW: where did the '007 bit come from? 007 can be a girl, you know!

PC drives me nut's sometimes...

"I'm just setting up for the T. fluvilatus, if you were not keeping your last baby - I'd be tempted to offer it a home also. Mbu's are out for now but give me time...!" -- soggydrysuit

I'm confused -- what do you mean, "if I were not keeping my last baby ....." ?

And the 007 came about last year when Daniel Craig as 007 was all over everything. I just thought it was a funny joke, but now I just think my user name is stupid and would very much like to change it if I could.

As to my SG, I will have to take another reading tomorrow, because I think the temp wasn't right, and I believe that makes a difference.

I've been keeping brackish tanks for over a year, with no problems, but just wasn't sure if it still mattered about crashing the filter if I add too much salt by accident.

And mudskippers are just too cool, you should get some, lovely little fish they are, I would not want to be without them -- EVER!