Salinity - ppt vs S.G. (Need Help Knowing How To Properly Measure)

[JSkeleton]

The more often you replenish evaporated water the more stable your salinity will be. I would never run a tank without an ATO of some kind.
Fish can stand a huge range of salinity, but corals need to be closer to that 35 range.

I'm not sure that I can get an ATO at the moment. Do they require a lot of space?

 

[Jedi1199]

I'm not sure that I can get an ATO at the moment. Do they require a lot of space?

An ato is a small controller unit. it has a sensor that attaches to the tank or sump to recognize when the water level has dropped below ideal. This sends a signal to the controller to turn on the pump which is inside the reservoir container.. The pump will start sending fresh water from the reservoir to the system until the sensor sees that it is filled back to ideal and tells the controller to stop the pump.

So the ATO is small, the reservoir is up to you. A 5g bucket, 20g garbage can, whatever.

 

[JSkeleton]

I'm sorry.. Mixing threads again. I was thinking you had a 13.5 evo.

I had a 55g for the last 18 months or so. I did top-offs by hand. Usually about 2 or 3 gallons every few days. With a tank that size, the evaporation is not going to cause much of a change in the overall parameters.

That said, it is still a good idea to have an ATO on your system. The less things change, the better.

Keep in mind that an ATO is worthless if you don't refill the reservoir. It's very easy to forget about it after you fill it up. Your brain says "I am good for a while" a few days later you realize it has run dry...

Oh boy, so for a 55g how often would you burn through say 5g in an ATO?

Also, would you happen to have a good ATO in mind to recommend? Upon a quick search the "AutoAqua Smart ATO Micro" seemed good but maybe not the best? My wallet is already hurting and to be fully honest I'm already partly regretting going saltwater and not just going freshwater again, but I'm this far now haha

 

[Jedi1199]

Oh boy, so for a 55g how often would you burn through say 5g in an ATO?

Also, would you happen to have a good ATO in mind to recommend? Upon a quick search the "AutoAqua Smart ATO Micro" seemed good but maybe not the best? My wallet is already hurting and to be fully honest I'm already partly regretting going saltwater and not just going freshwater again, but I'm this far now haha

I am not into brands. If the tool works it works. I won't spend $500 on a tool I can get for $50 just to get a brand name on it.

This is the ATO that I use on my tanks.
Amazon product
For the pump, I got a small fountain pump from Harbor Freight. For the reservoir, I have 5g buckets. I do intend to go much larger for the new 135g that I just built. I will utilize the coat closet to house the container. I will use the same JBJ unit I linked to for the ATO for that tank as well. Currently I top that one off by hand.

 

[JSkeleton]

I am not into brands. If the tool works it works. I won't spend $500 on a tool I can get for $50 just to get a brand name on it.

This is the ATO that I use on my tanks.
Amazon product
For the pump, I got a small fountain pump from Harbor Freight. For the reservoir, I have 5g buckets. I do intend to go much larger for the new 135g that I just built. I will utilize the coat closet to house the container. I will use the same JBJ unit I linked to for the ATO for that tank as well. Currently I top that one off by hand.

I can't see what you linked for some reason.

So just a cheap $20 fountain pump or something with it?

And yeah I was thinking of just using a 5g bucket as well if I do get an ATO. 135g, wow!

 

[Jedi1199]

I can't see what you linked for some reason.

So just a cheap $20 fountain pump or something with it?

And yeah I was thinking of just using a 5g bucket as well if I do get an ATO. 135g, wow!

Search Amazon for JBJ auto top off. The unit I linked is about $90

 

[Jedi1199]

My current reef system.

 

[JSkeleton]

My current reef system.

Oh man, that's a nice system!

 

[JSkeleton]

No, it is not doing it more accurately. It is just doing a mathematical calculation for each result from the actually measured conductivity.

It shows more precision as ppt, but with a claimed accuracy of +/- 1 ppt, the ability to read to 0.1 ppt is not of much value.

Slightly off (but still on) topic...you mentioned mathematical calculations which got me thinking. 35ppt = 35g of salt per Liter of water, correct? How would I go about figuring how much salt to measure when mixing per gallon? Is there a certain equation or something? Everywhere I search goes by Grams for salt, but I (and I think a lot of people) go by Cups. Yet, I can't find any definitive answer on how many grams are in a cup, since grams are weight and cups is more of a measurement.

 

[firechild]

Oh okay! But isn't SG based partly on temperature or? And are there accurate ways to convert (such as the calculator Eric linked), are conversions generally accurate?

As I asked him, for example, judging by a conversion Clownfish are best kept at 28-33ppt (if I was to use ppt that is)?

It depends how the measurement is being taken but it will be taken as one and converted to the other. For example, if it is using density or refraction, it will be measuring in SG and then converting to ppt. If it is measuring conductivity, it will be measuring in ppt and converting to SG (actually it is starting with mS/cm, then to ppt, then SG). If the instrument is unable to take its own temperature measurement to convert precisely, it will likely use standard temperature and pressure which is 25 degrees celcius and 1 atmosphere. 25C is within the range that we keep our aquariums and unless you live high in the mountains, 1 atmosphere is going to be pretty close to the mark too. Many instruments will account for temperature but none used in the industry (at least at a hobbyist level) that I am aware of will account for pressure, so there's a chance that there will be a very small amount of imprecision.

I would question the validity of the idea that clownfish (which naturally live in the same ocean as everything else) should be kept in a permanent state of hyposalinity.

 

[firechild]

Slightly off (but still on) topic...you mentioned mathematical calculations which got me thinking. 35ppt = 35g of salt per Liter of water, correct? How would I go about figuring how much salt to measure when mixing per gallon? Is there a certain equation or something? Everywhere I search goes by Grams for salt, but I (and I think a lot of people) go by Cups. Yet, I can't find any definitive answer on how many grams are in a cup, since grams are weight and cups is more of a measurement.

Yes, 35g/L. Easiest way is to measure the weight of a full cup. I have a set of digital scales I use only for measuring salt. I use 2.1kg for my 60L drum.

 

[Jedi1199]

Look here for a conversion table..

www.onlineconversion.com

You can pretty much convert anything into anything there.

The thing with mixing salt is checking the final product. There is no set table that says, x grams of salt= this specific gravity. We add, then test and then adjust. I know that for refilling my mixing can after a water change I need about 8 cups of salt... but I never add it all at once... I add 6, let it mix, test and adjust as needed.

 

[JSkeleton]

Yes, 35g/L. Easiest way is to measure the weight of a full cup. I have a set of digital scales I use only for measuring salt. I use 2.1kg for my 60L drum.

In that case you would first have to measure how much your measuring cup weighs to substract from the final weight with salt, right?

 

[JSkeleton]

Look here for a conversion table..

www.onlineconversion.com

You can pretty much convert anything into anything there.

The thing with mixing salt is checking the final product. There is no set table that says, x grams of salt= this specific gravity. We add, then test and then adjust. I know that for refilling my mixing can after a water change I need about 8 cups of salt... but I never add it all at once... I add 6, let it mix, test and adjust as needed.

Does that site properly convert grams to cups though since grams are weight dependent?

Ah yeah that is true. I'm not expecting an exact specific amount, just trying to get a ballpark idea to work off of cause as of right now I just add bit by bit inching it slowly and gradually closer to my target which is annoying and tedious haha

 

[firechild]

In that case you would first have to measure how much your measuring cup weighs to substract from the final weight with salt, right?

Maybe. Most digital kitchen scales have a button (Tare) to zero the weight after you've placed your cup on it. This means the weight displayed will be only the salt.

 

[Jedi1199]

Does that site properly convert grams to cups though since grams are weight dependent?

Ah yeah that is true. I'm not expecting an exact specific amount, just trying to get a ballpark idea to work off of cause as of right now I just add bit by bit inching it slowly and gradually closer to my target which is annoying and tedious haha

I may be mistaken, but it still seems to me that you are confused by the difference between metric and imperial.. a dry cup is a dry cup, a metric gram is a gram.. there is no difference here.

Let me help you out.. A dry cup weighs 4.5 oz or 128g.

That figure should help you measure in metric.

For a table of the conversion rates, you can look here...

Cup to Gram Conversions

Be accurate! This chart helps you convert measurements from cups to grams and ounces, depending on what your recipe calls for.

www.allrecipes.com

 

[Jedi1199]

Ok.. I take the back... According to my kitchen scale, 1 cup of Reef Crystals weighs 290 grams.

 

[Jedi1199]

Again... the point is irrelevant... weather you measure in cups or grams, the goal is 35 ppt. this is best achieved by adding salt, testing, and adjusting. Knowing if 4000g is the target is pointless... You may not have the same amount of water to start from, you may have leftover saltwater at the beginning. Its all based on repeated process and best estimate.

 

[JSkeleton]

I may be mistaken, but it still seems to me that you are confused by the difference between metric and imperial.. a dry cup is a dry cup, a metric gram is a gram.. there is no difference here.

Let me help you out.. A dry cup weighs 4.5 oz or 128g.

That figure should help you measure in metric.

For a table of the conversion rates, you can look here...

Cup to Gram Conversions

Be accurate! This chart helps you convert measurements from cups to grams and ounces, depending on what your recipe calls for.

www.allrecipes.com

Yeah, I did get pretty lost not gonna lie haha It may be simple, but mathematical things were never my strong suit

I get it now, though! That said, that means to measure say 35ppt properly, you would need to weigh it, which is why it seems many people do such I guess eh?

At the same time, if 1 Cup typically = roughly 128g, then to get 34ppt: 128/34=3.76L which is about 0.99 Gallons, so in theory, 1 Cup would give me roughly 34ppt per 1 Gallon? Or do I have that wrong cause it does seem a bit high?

Maybe I should just buy a scale‍Lol

 

[Jedi1199]

I mix my water in a 32g brute can. I use a 20g can for the waste water. so in essence I have about 10-12 gallons of mixed saltwater left over when I am finished. I refill with fresh RODI water and add salt till I reach the desired 35 ppt. I do not have a determined measurement for this.. I add a few cups.. it could be a standard cup, it could be an old butter container it could be a thimble!! I add salt, check my salinity and adjust. This is how the game is played.