How quickly do you add salt?

PDR · May 1, 2018

I have read countless threads about what kind of salt to use, how long to let your salt mix, etc. But what I have not run across is the method people use for adding salt to the water.

The only thing I have ever read in this regard is to add salt to water, not water to salt and to not add salt "too quickly". Well what is considered the correctly method/timing?

I mix my salt 25 gallons at a time and usually measure out 13-14 1/2 cups one right after the other. I just shake them in one at a time but I don't wait between the scoops. Should I? I remember reading somewhere about adding too quickly can cause precipitation and possibly other issues.

Can anyone shed light on this for me?

Thanks!

JoshH · May 2, 2018

Interesting question, personally I do the same as you with no Ill effects. I do believe in mixing my RSCP salt in cold water first and then heating afterwards, definitely keeps it from getting cloudy. But I make 5 Gallon buckets and just pour 1 cup in at a time and after a minute I move the pump around to stir up anything that didn't mix in the first time, as long as I don't splash I'm happy. #Reefsquad how do you mix your salt?

Sabellafella · May 2, 2018

I can vouch for pouring in slowly. I bag 10 cups of salt into the lfs fish bags so I can have them ready after my container fills with rodi. The few times I've dumped it all in at once, I had somewhat cloudy water. So now i just shake the bag in here and there

Mr. Bill · May 2, 2018

I just scoop my salt into the water and let the old Maxi-Jet 1200 do the rest. Never noticed any difference between heating before or after adding the salt, either. Personally, I like to aerate the water for a few hours after mixing, so I don't believe how you add the salt really matters.

Martin Kuhn · May 2, 2018

Always did it like this and never had any issues
- prepared RODI
- heated up to 25 C / xx F
- measured the amount of salt needed using a weigh (proper amount calculated with AquaCalculator beforehand)
- thrown / switched on a pump in my RODI container
- threw in salt
- waited 5 min for mixing (water was never cloudy afterwards)
- used this time to lower the water level in my tank
- pumped in new salt water to my tank

ntayler · May 2, 2018

I have a mixing station in the garage. I just dump a whole bag into 45 gallons of rodi as fast as it will pour. It’s cloudy as heck at first but clears up in a couple hours. I make my water ahead of time so pump mixes it for a day (or 2 or 3) until I do my water change and pump it to the tank.

chipmunkofdoom2 · May 2, 2018

I used to measure my salt in grams. So, for my 22 gallon Brute, I know I would need 3,432g of salt. I would portion out a third of that at a time, and I would dump the third into the Brute trashcan slowly. I'd let it dissolve for a bit, then dump the next third. I'd do the last third a short time later.

I've since moved up to a 44 gallon Brute for mixing saltwater. Now, I snip the corner off a 50 gallon bag of Instant Ocean and slowly pour the bag into the Brute over 5 minutes or so. The water is a bit cloudy, but it clears up in a day or two. At that point I turn off the pumps and pump out what I need when I need it.

With regard to the temperature of the deionized water, in general cooler is better. Some of the constituents in salt mix (like calcium chloride) produce heat when they are mixed with water. This localized heat can cause calcium carbonate precipitation. Cooler water will help minimize this effect. I'm not sure I'd go as far as making sure I use cold water, but my water happens to come out of the DI stage very cold in the winter and I never heat it before adding salt.

reefwiser · May 2, 2018

Aquaforest Salt mixing
Res Sea salt mixing
Insant Ocean mixing.

ESV salt mixing it's what I use.
An Mr. Salt water tank talks you thru it.

Greybeard · May 2, 2018

Dump it in using a plastic cup... fairly rapidly. I mix in a brute can, with a Mag 12 pump, so it's very turbulent. I always let it mix for a minimum of 4 hours before using it. Generally, it's several days, but I can't get the temp up where it needs to be in less than 4 hours.

Fritz RPM salt, and I have very, very little precipitate. Water is crystal clear, no crust or residue left in the barrel afterwards.

Oh, and I rinse the barrel out every few months. I've seen mixing stations that were just nasty. Dusty, dirty, crusty... I can't imagine using that container to store my nice, clean RO/DI and new salt water.

PDR · May 2, 2018

Thanks for all the replies! You all have been very helpful as usually!

redfishbluefish · May 2, 2018

Here is my mixing routine for 25 gallons of water in a 32 gallon Brute:

1. Water - the full 25 gallons of RO/DI water unheated. It might be counterintuitive, but the calcium part dissolves better at cooler temperatures. So ideally, don't heat your water until the salt is dissolved.

2. Agitation - give the water as much aggitation as possible. I remember someone who use to use a canoe paddle to mix his salt. I have two old-school Koralia powerheads in my 32 gallon Brute....a K4 and a K8.

3. Bag or Bucket - I prefer the 200 gallon mixes that come with 50 gallon bags of salt. If you're a bucket user (ca160 gallon), roll the bucket around to mix the salt. Some of the small ingredients could settle, causing for different mixes at the beginning and end of that bucket.

4. Salt Add - add the salt like you're salting a large portion of popcorn. If it's simply dumped, micro-environments could cause too high concentrations and cause precipitation of calcium carbonate. I add a cup at a time and each cup takes maybe 5 seconds or so to dump into the water....salting popcorn.

4. Heat and Salinity - Right before I'm ready to do a water change, I heat the water. Once the water is heated, I measure salinity with a refractometer. Even though I have a so-called temperature compensated refractometer, I've noticed the SP is higher when the water is cold. So I wait until the water is 78F and then do my final adjustments of salinity. Note with a refractometer, use calibration fluid, not RO/DI water to calibrate.

The DON'Ts:

a. Don't add water to salt
b. Have the full volume of water. That is, don't make a "concentrated" salt solution because you're still making water that you will add later. Wait until you have the full volume of water.

Susan Edwards · May 2, 2018

Usually I heat first, then add what I think I'll need to a smaller bucket and dump it in. I use a wooden spoon to stir (32 gal brute can), turn on my pump and let it circulate the water. I always let it sit as it seems to get stronger in salinity after a couple hours. So I try to add a bit less than I think I'll need. I keep some of the extra salt water in jugs for emergencies, so if it is not right in the can, I can add some from the jugs

|sCRIBe| · May 2, 2018

I do 10-15 gal at a time starting with filling the container with rodi water and once there’s enough water to cover the heater I turn the heater on and let the container continue to fill until the container is full. Then I plugin a strong power head to get the water moving and add my salt, 1 cup at a time and let that all mix up until the water is clear. By the time it’s clear and mixed the temperature is also adequate and ready for the tank. I always do a final salinity check before adding the water. Never had a problem with this method.

Bent17 · Apr 22, 2023

Hoping you guys can help. Trying to get the perfect salt weight to pour into my 50L RODI to make life easier and faster to have the correct salinity. Last week I added 1,800g and it was quite low, today I did 1,900g and its at 42 salinity! Only thing I did was dump most of it in fast and leave the pump circulate. Does dumping it in make a big difference compared to slowly adding it?

redfishbluefish · Apr 22, 2023

You want as much agitation as you can provide. (for my 25 gallons that I make, I have two old powerheads in the 32 gallon Brute...a Koralia K4 and K8).

You then want to sprinkle the salt into the swirling water. The reason you just don't dump it in is because you don't want to create a micro-environment of high alkalinity and calcium...it will cause it to precipitate. And I don't mean to make this sound like this requires great precision....it can still be relative sloppy.

As far as weight, I can't help. But what I do to help sprinkle the salt into the water is to use a measuring cup. (One US cup measure). Using a measuring cup allows me to sprinkle in the salt. For each 5 gallons of water, I add 3 cups of salt (regular purple colored Instant Ocean). This gets me very close to 1.026 salinity where it's right on the money or requires a touch more of salt or a splash of water.

Bent17 · Apr 22, 2023

Could possibly be the issue. Could it actually increase salinity if you just dump it?

redfishbluefish · Apr 22, 2023

Bent17 said:
Hoping you guys can help. Trying to get the perfect salt weight to pour into my 50L RODI to make life easier and faster to have the correct salinity. Last week I added 1,800g and it was quite low, today I did 1,900g and its at 42 salinity! Only thing I did was dump most of it in fast and leave the pump circulate. Does dumping it in make a big difference compared to slowly adding it?

This is odd??? Since I was making fresh saltwater, I figured I'd weigh out some to see the weight of salt needed using Instant Ocean Salt. As stated above, I simply use cup measurements to get me in the ballpark of 1.026 (35ppt). I only weighed 3 cups (which is what I'd use to make 5 gallons). I'm including my math in case I've made errors in my calculations. Again, this is for Instant Ocean, the purple box. Other salts might weigh differently, resulting in different salineties.

3 cups (US) weigh 854 grams
5 gallons (US) equals 18.9 liters

854 g / 18.9 L x 50 L = 2259 g

That is, using Instant Ocean, you would need 2259 grams in 50 liters of water to get to approximately 1.026 (35ppt) salinity. What I find odd is that you were only in the 1800 - 1900 grams of salt, where 1900 grams resulted in 42 ppt. Now I could understand a difference in salinity with different salts, but not one this large.

It appears you will have to determine the amount of your specific salt on your own.

redfishbluefish · Apr 22, 2023

Bent17 said:
Could possibly be the issue. Could it actually increase salinity if you just dump it?

I wouldn't think so. Micro-environment of high alkalinity and calcium would potentially cause precipitation of calcium carbonate thereby lowering the measured alk and calc numbers.....not salinity.

pennied · Apr 22, 2023

Pistondog · Apr 22, 2023

1. Dispense rodi into 42 gallon brute.
2. Heat to 75 f overnite, maxijet 1200 running all the time
3. Heater off
4. Pour in some salt.
5. Stir 10 secs with short kayak paddle
6. Wait at least 1 hour, maxijet running
7. Measure salinity, if < 1.025 goto 3
8. Done, leave maxjet on