Dealing with rising salinity in small reef tanks

[Brandon McHenry]

Hi fellow reefers!

I wanted to see how other reefers with heavily stocked nano/small reefs deal with salinity creep. My tank volume is probably around 35g and is full of large SPS colonies (pictured below for reference). I currently dose 100mL of BRS two part as well as fully saturated kalkwasser in my ATO. I do weekly 5g water changes (with TM Pro at 34ppt) as well as the occasional freshwater exchange to drop salinity. I calibrate my refractometer weekly and I am always at 36-37ppt. Just curious if anyone has any other methods to managing rapidly rising salinity other than the freshwater replacements. Thanks in advance!

 

[mdb_talon]

For starters... that's a beautiful tank you have!

In the past I had this issue when I ran a 20g that was heavily stocked with SPS and think it really only is an issue if you have to dose a ridiculous amount (which for a small tank I think you qualify lol).

As far as I am aware there is not a good way to handle it other than switching out some saltwater with fresh as you indicated you occassionally do; or using a lower salinity on water changes. In my scenario I did weekly water changes and found that it handled the salinity creep in my scenario just fine. I targeted 1.026 and in a week it was about 1.027 so I used around 1.023 replacement water and it seemed to keep it pretty stable in that 1.026-1.027 range. Was not ideal, but it worked.

 

[BeardedDragon21]

What is the salinity of your ATO? If it has any salinity you'll naturally get an increase over time from the evaporation and replacement. Love love love the tank!

 

[mdb_talon]

What is the salinity of your ATO? If it has any salinity you'll naturally get an increase over time from the evaporation and replacement. Love love love the tank!

I am sure his ATO is using pure RODI no salinity. The issue though is when you dose two part only part of it gets consumed by corals... it leaves behind sodium. This causes the creep... and why it only really usually an issue in tanks with massive demand relative to water volume. At least that is what I remember from when I looked into it. I am sure someone can do a better job of explaining the chemistry though.

 

[Brandon McHenry]

For starters... that's a beautiful tank you have!

In the past I had this issue when I ran a 20g that was heavily stocked with SPS and think it really only is an issue if you have to dose a ridiculous amount (which for a small tank I think you qualify lol).

As far as I am aware there is not a good way to handle it other than switching out some saltwater with fresh as you indicated you occassionally do; or using a lower salinity on water changes. In my scenario I did weekly water changes and found that it handled the salinity creep in my scenario just fine. I targeted 1.026 and in a week it was about 1.027 so I used around 1.023 replacement water and it seemed to keep it pretty stable in that 1.026-1.027 range. Was not ideal, but it worked.

What is the salinity of your ATO? If it has any salinity you'll naturally get an increase over time from the evaporation and replacement. Love love love the tank!

I am sure his ATO is using pure RODI no salinity. The issue though is when you dose two part only part of it gets consumed by corals... it leaves behind sodium. This causes the creep... and why it only really usually an issue in tanks with massive demand relative to water volume. At least that is what I remember from when I looked into it. I am sure someone can do a better job of explaining the chemistry though.

Thank you for the compliment! And yes youve got it right. The reason my salinity creeps up the way it does is because of the huge demand of my corals and the amount of two part that must be added on a daily basis (leaving behind the sodium and chloride ions). I figured that the main way people handle this issue is with freshwater replacements (or the lower salinity water changes).

 

[Brandon McHenry]

And yes my ATO is pure RODI with kalkwasser.

 

[Acroporaguy]

I'll also be following along. I have a nano with almost purely SPS and I can observe a salt creep as well. I'm dosing a ton of two part so I'm sure that's why. Every week or so I remove a bit of water and let the ATO top off with RODI.

 

[Brandon McHenry]

I'll also be following along. I have a nano with almost purely SPS and I can observe a salt creep as well. I'm dosing a ton of two part so I'm sure that's why. Every week or so I remove a bit of water and let the ATO top off with RODI.

Same boat here!

 

[NexisG]

I don’t have a beautiful sps tank like yours so I don’t really deal with this problem but if you run a dry skim you could try making it wet instead. I think that would keep the salinity down somewhat but then you have to empty the skimmer cup more often.

 

[Brandon McHenry]

I don’t have a beautiful sps tank like yours so I don’t really deal with this problem but if you run a dry skim you could try making it wet instead. I think that would keep the salinity down somewhat but then you have to empty the skimmer cup more often.

Well thank you for the compliment! I have thought of that but it’s an AIO tank so the skimmer is very small and probably holds only a cup of water so I think the impact would be negligible unfortunately.

 

[mkwarner77]

I'd reduce the salinity of the water changes, but I wouldn't worry about it to much. The way your tank looks the corals obviously love the water conditions.

 

[schuby]

If I had this issue, then I'd set my AWC to remove more than is put in. This would create a net-less amount of saltwater that would be replaced automatically by my ATO. The result would be a constant, small replacement of saltwater with freshwater.

 

[Justin Swinney]

Hi fellow reefers!

I wanted to see how other reefers with heavily stocked nano/small reefs deal with salinity creep. My tank volume is probably around 35g and is full of large SPS colonies (pictured below for reference). I currently dose 100mL of BRS two part as well as fully saturated kalkwasser in my ATO. I do weekly 5g water changes (with TM Pro at 34ppt) as well as the occasional freshwater exchange to drop salinity. I calibrate my refractometer weekly and I am always at 36-37ppt. Just curious if anyone has any other methods to managing rapidly rising salinity other than the freshwater replacements. Thanks in advance!

I dose tropic Marin part c with the brs two part. Quit rising on me whatever you dose in cal and alk dose in part c ie 20ml alk + 20ml cal = 40ml TM part c

 

[Brandon McHenry]

I'd reduce the salinity of the water changes, but I wouldn't worry about it to much. The way your tank looks the corals obviously love the water conditions.

Very true lol but it does creep up to the point that I’d prefer to lower it.

If I had this issue, then I'd set my AWC to remove more than is put in. This would create a net-less amount of saltwater that would be replaced automatically by my ATO. The result would be a constant, small replacement of saltwater with freshwater.

Unfortunately I don’t have an AWC system (all manual here lol) and my ATO has saturated kalk so I’d have to add the freshwater back manually.

I dose tropic Marin part c with the brs two part. Quit rising on me whatever you dose in cal and alk dose in part c ie 20ml alk + 20ml cal = 40ml TM part c

I use the same but it should still rise. I dose a little over 5 times that amount which is why the increase is more profound.

 

[TheDragonsReef]

Could just take a cup of water out of the tank and add a cup of straight rodi a couple times a week or something. If you got some dosing pumps you could do it automatically.

 

[Justin Swinney]

Very true lol but it does creep up to the point that I’d prefer to lower it.



Unfortunately I don’t have an AWC system (all manual here lol) and my ATO has saturated kalk so I’d have to add the freshwater back manually.



I use the same but it should still rise. I dose a little over 5 times that amount which is why the increase is more profound.

Wild

 

[Brandon McHenry]

Could just take a cup of water out of the tank and add a cup of straight rodi a couple times a week or something. If you got some dosing pumps you could do it automatically.

Yeah that’s pretty much where I’m at lol