Many Thanks To Bigc And Steelhealr

[Crazy fishes]

Since yesterday I have be adding more salt like recommended; just out of curiousity how much salt would you have to add to a 24g tank at 25C to get a s.g of 1.023. I have added what feels like loads yet I still haven't reach that value (s.g=1.023).
I have also opened up the rock comformation and moved rocks forward. It isn't as high as I wanted but I looks really good. Many thanks once more guys (or possibly Girls??)

Regards

 

[nanocubeking]

How much have you all ready added.

 

[Crazy fishes]

How much have you all ready added.

A good few kilos and I am just on the verge of reaching s.g 1.023!! Is that the norm??

Regards

 

[steelhealr]

I mix my salt and water first with a heater, powerhead, etc. In 5G's of RO water, it takes me about 6 full cups to attain 1.026. So..you can estimate that in a 24, you'd need almost30 cups. People don't appreciate how much salt it takes to make sw. SH

 

[dilbert]

How much have you all ready added.

A good few kilos and I am just on the verge of reaching s.g 1.023!! Is that the norm??

But you shouldn't add more than 4 kilos. (i.e. 44 g * 24 liters * 3.8 factor liters/gallons)

Sorry now for mixing metric and imperial units but you can easily convert them ... LOL

You should have an instruction with your salt telling you how much salt to mix. Often it is 35 g per liter or so. That can become more if the salt has been stored in an open bag as it attracts humidity from the air.

I am unfortunate to use a no-name salt without any instructions and I use generally 44 g per liter to make water of SG 1.025.

Measuring by weight cannot be the only method as you don't know how much humidity is in there.

On the other side, you must rule out that your refractometer or what you are using would have an significant error. An SG over 1.030 can become life threatened to many marine animals.

So the best thing is to corner the uncertainties is
1. following painstakingly the instructions to mix your salt
2. have your instrument calibrated as best as you can and check what error is has
3. don't go on the limits of the SG if there is no special reason, stay in the middle, but better too low than too high

 

[piranha_trader]

Forgive me for hijacking your thread but I thought it would be simpler to ask a question related to salinity rather then opening up another thread on the topic.

After killing off dwellers in my tank by supplying them with instantly made instant ocean (rather than waiting a day or two to calm the minerals out), I went ahead and bought about 3, 5-gallon buckets and went to the east side of Oahu to glean natural water for my tank. Why the east side? Well this is where famed Hanauma Bay is and Sandys Beach (actually very close to where I collected) and also because the area is as close to true wilderness than Im going to get near. There are no harbors, serious boating, jetskis...etc. Very low probability of pollutants.

Anyways, I noticed that the water salinity was high...about 1.027-29. High but things here frolick.


Im just wondering if/when I need to ever mix instant salt, if I should mix it to this salinity level or if natural salinity matches instant ocean salinity in the 1.023 range....just not sure what to think here.

Any expert opinion is welcome.

PT

 

[1entra]

Well I have read up somewhere that natural sea water has a s.g. of around 1.026 so you can mix up to that but most people tend to stick with about 1.024-1.025

 

[dilbert]

The salinity levels of the oceans vary actually. There are map and tables on the Internet.

Furthermore, the salinity of a particular rock pool, lagoon, or other locations can be different from the surrounding ocean.

At first, every instrument has an error even when properly calibrated (my electronic conductivity meter has +- SG 0.002 from the datasheet was is quite much). At second, if not properly calibrated (long time not calibrated or faulty calibration liquid used) you will get added a further error.

So, you see for the hobbyist it is quite difficult to get exact resullts even with a refractometer from the cheaper price range. That's why I try to stay in the middle so that an error doesn't hit the limits.

Some people actually state they would have SG 1.027 in their tank. Maybe they try to mimic the Red Sea or they have other reasons. Perfectly fine, if they have instruments more exact than I have.

Then, some people think that fish do better at lower salinity or try to save on salt or whatever and go with SG 1.022 and even lower.

But AFAIK, more animals are stressed with salinity too high than too low.

I would try to find out from local sources what the salinity is around Hawaii and if there are specific differences in some locations. That is just to compare it with your results. They might have used better instruments to get more correct figures but those might be decades old and not up to date anymore.

Then I would try to find out what particular animal appreciates really a higher salinity and if not I would stay in the middle of the recommend figures what is SG 1.023 to 1.027 I guess.

 

[andywg]

There is some mixing of terms here. Salinity is not SG. SG measures the weight of the water in comparison to the weight of pure water (with pure water being 1.000). SG is affected by temperature. there is a very good chart in Reef Fishes Volume 1 (may be in 2 and 3, I can't recall) which tells you how much to alter the reading at different temperatures.

Salinity refers to how much salt is in the water and is measured in parts per thousand. Most of the oceans are around 35-36ppt which at 25 degrees C (I am racking my brains here, but I think I am close) comes out around the 1.026 level. I can check tonight and give some ideas for anyone interested.

I would wager that very nearly none of us actually meaure salinity, we either measure the specific gravity (hydrometer), or the refractive index (refractometer) which is then converted to salinity.

Also, most fish are more tolerant of varying salinities, and the fish (as commented on by Dilbert) are far more tolerant of lower salinities (down to 15 ppt and even lower for very brief times) but generally far poorer at dealing with raised salinities.

The reason to keep salinities lower is touched upon above by Dlibert in that it save money on salt in a system which is likely to be a heavier load than a reef, and thus benefit from more frequent water changes.

 

[dilbert]

You're perfectly right, Andy, and unfortunately, you're not the first one mentioning my sloppy use of salinity and SG.

Maybe it has to do with SG being firstly an abbreviation, secondly a general term from physics, so that SG on its own sounds maybe somewhat cryptic to someone new on marine and reefs.

Salinity on the other hand is a term easy to grasp but its unit ppt is not very common.

Maybe I should try "saltwater SG" as it shows the appropriate figure that people are common with and people new to the hobby can imagine that it's a figure that has to do with the characteristics of saltwater ... the amount of salt in it, presumably, ... salinity !!!.


That only to keep up good habits for not to end up like an owner of an LFS who talks about "an SG of 25" when he actually means "SG 1.025".

 

[Crazy fishes]

You're perfectly right, Andy, and unfortunately, you're not the first one mentioning my sloppy use of salinity and SG.

Maybe it has to do with SG being firstly an abbreviation, secondly a general term from physics, so that SG on its own sounds maybe somewhat cryptic to someone new on marine and reefs.

Salinity on the other hand is a term easy to grasp but its unit ppt is not very common.

Maybe I should try "saltwater SG" as it shows the appropriate figure that people are common with and people new to the hobby can imagine that it's a figure that has to do with the characteristics of saltwater ... the amount of salt in it, presumably, ... salinity !!!.


That only to keep up good habits for not to end up like an owner of an LFS who talks about "an SG of 25" when he actually means "SG 1.025".

Anyway I have managed to get my S.G to 1.024 with the pumps off!! Presumably this is the actual S.G as opposed to when the pumps are on and the flow through generated causes significant lift of the needle. I hope that is right or my S.G is in the 1.028-1.029 kind of range !!!??? Measurements are with a hydrometer.

Joe.

 

[timpetty]

Would it be possible to take a water sample to your LFS and match your hydrometer results with what he/she gets?

 

[dilbert]

If you haven't compared recently the readings from your hydrometer with the readings from another instrument you can trust better, I would do so.

Best thing would be to go to an LFS and ask him to check your hydrometer or buy some salted water with known SG or anything like that.

There are also some instructions to mix your own standard with table salt but if make there the slightest mistake then this is very dangerous as you would trust in a wrongly set up calibration liquid.

Does your marine salt come with an instruction like 37.5 grams per liter for SG 1.025 or so? Then mix one liter. You would need a balance down to 1 grams for that. Greater supermarkets sell this in their kitchen tools department for around GBP 10 for an electronic balance. Just make sure the smallest unit is grams or ounces.

Unfortunately, all those methods can bear an error of about +- 0.02 or so, so the best method is to compare your hydrometer with another more precise instrument.

PS:
Sorry, again too slow. Didn't see the earlier post.

 

[steelhealr]

OK...I'm sorry but I have to say this:

Specific gravity.....s.g......is what you are all talking about...NOT salinity.

Salinity is a percentage and is independent of temperature.

S.g. gravity is dependent on temp.

My tank runs at a specific gravity of 1.026 and at 80 degrees has a salinity of about 35%.

SH

 

[steelhealr]

Someone asked me make a comment on where to keep your tank with regards to specific gravity. This is a personal choice but should be based on what you keep in your tank. I did a lot of research on this in my early days when first getting into nano reefing. This is what I go on but, remember, opinions may vary.

Many publications I have read and some articles from more published aquarists tend to run their tanks high. Average ocean s.g. is closer to the 1.025-1.026 range, however, this will vary based on where samples are taken. EG, some corals such as nemanzophyllia prefer 'dirty lagoons' that are high in nutrients and this comes from runoff from the beach/shore. In areas of heavy rainfall and runoff, the s.g. gravity runs lower than areas of deep ocean. In my area of NY, the s.g. of Long Island Sound near the beach (yes, I tested) runs about 1.023.

Overall, I prefer to run my reef at what I would consider to be Carribbean specs, as I have understood them to be. I run my tank at 1.026 and low 80's. Like SkiFletch, I am an avid ocean scuba diver. I dive with a dive computer and at 30-40 FSW, my temps came in between 79-81. There may be some advantages and disadvantages to where you run your s.g. with regards to your fish:

• running your tank at a lower s.g. may help with fighting fish disease however, this may stress your corals causing them to dump their zooxanthellae, bleach and die
• if you run your tank where I do at 1.026 and you are NOT religious about topping off, your s.g. may climb and stress the fishes excretory system.

Each nano reef keeper should choose their own methods for running their tank. If it works, stick with it. If it doesn't, try something new. The bottomline here: before adding sodium bicarb, strontium, molybdenum, iodine, Purpler Upper Your Tank And Empty Your Wallet Stuff, etc, step back and look at your tank. Is it doing well? Then don't treat numbers. DO MAINTAIN YOUR CALCIUM/BUFFER system tho'.
Short post on s.g.

SH