Accounting for skimate?

[PeterEde]

At present I do manual top off. But will need an ATO when I travel and will be away for weeks.
An ATO accounts for all water loss, evaporation and skim.
The question is how do you account for actual salt water loss?
An ATO with RODI water alone will reduce salinity.

My routine now is measure the skim and replace with equal amount of salt water. Any water drop after that I top off with RODI.

Thoughts?

 

[TangerineSpeedo]

Well, you could do an average of Skim loss and set up a separate dosing container with a dosing pump.

 

[exnisstech]

I've never thought about the water loss from skimate. I just let the ato pump in RODI and salinity had stayed at 1.025 for the few years it's been up. Do you have a small system where it may be more of a concern?

 

[mdb_talon]

Hard to imagine it making an appreciable difference unless you skim extremely wet or have a very small tank. Personally never noticed a reduced salinity due to use of ATO and a skimner. Maybe if i was using a digital salinity tester with some extra decimal points i could see the change, but with my refractometer it all looks the same with these old eyes.

 

[Gtinnel]

There are several things that effect salinity but aren’t big enough to be a major concern. Skimmate and salt creep will lower salinity, while 2 part dosing will raise salinity.

Surely I’m not the only one who has to occasionally add in a little extra saltwater to make adjustments to salinity. I always assumed mine was mostly because of fluctuations in my AWC salinity though.

 

[gbroadbridge]

At present I do manual top off. But will need an ATO when I travel and will be away for weeks.
An ATO accounts for all water loss, evaporation and skim.
The question is how do you account for actual salt water loss?
An ATO with RODI water alone will reduce salinity.

My routine now is measure the skim and replace with equal amount of salt water. Any water drop after that I top off with RODI.

Thoughts?

Don't forget that dosing to maintain Alkalinity and Calcium normally increases salinity.

So for me dosing 200ml a day input balances with 200ml of skimmate output.

 

[TangerineSpeedo]

When I do water changes i measure the salinity and I might do some Kentucky windage to raise or lower it a point or two to get to my ideal goal. I think the issue here is the OP is going to be away for "weeks" so keeping a stable salinity is a legit concern.
I was thinking, if it was in budget, a salinity probe with cloud based results and a doser that is also cloud based

 

[Ly78]

Unless the skimmer has auto cut off, safer to just skim drier or barely. In case somehow it decides to overskim and dirty water everywhere if its not in sump.

 

[Gtinnel]

So for me dosing 200ml a day input balances with 200ml of skimmate output.

Does adding a certain amount of 2 part increase the salinity by the same amount that an equal part of skimmate would reduce it?

I don’t know that it isn’t roughly equal, just curious if you know they’re equal or just showing that one increases salinity while the other is decreasing it.

 

[PeterEde]

I've never thought about the water loss from skimate. I just let the ato pump in RODI and salinity had stayed at 1.025 for the few years it's been up. Do you have a small system where it may be more of a concern?

Only 120ltr/30 gal

 

[PeterEde]

I guess I'll stop topping up salt to replace skim and see how salinity goes.

 

[monkeyCmonkeyDo]

If your skimmer is skimming so wet that it's removing your salt than id lower the water level inside the skimmer and maybe increase o2.
D

 

[Susan Edwards]

In 9 months I've not noticed any major change in salinity. I don't have a lot of watery skim, and the times when the skimmer overflowed due to chemi clean, I ran the drain into my socks so I wasn't tossing out water. Salinity seems to stay pretty stable.

 

[Lavey29]

Don't forget that dosing to maintain Alkalinity and Calcium normally increases salinity.

So for me dosing 200ml a day input balances with 200ml of skimmate output.

Can I ask for some validation for this statement? I find it intriguing because my salinity has nudged up to 1.027 and I can't figure out why this occurred. I water change at 1.026 consistently.

 

[gbroadbridge]

Can I ask for some validation for this statement? I find it intriguing because my salinity has nudged up to 1.027 and I can't figure out why this occurred. I water change at 1.026 consistently.

Well if you're using :

a) Sodium Bicarbonate/Carbonate for Alkalinity; and
b) Calcium Chloride for Calcium.

then:

The coral will take up the Carbonates from (a) and the Calcium from (b) to make Calcium Carbonate skeleton so you're left with Sodium and Chloride (NaCl) which is salt, subsequently increasing salinity over time.

 

[gbroadbridge]

Does adding a certain amount of 2 part increase the salinity by the same amount that an equal part of skimmate would reduce it?

I don’t know that it isn’t roughly equal, just curious if you know they’re equal or just showing that one increases salinity while the other is decreasing it.

I know that with the strength solutions that I'm using adding 100ml each of Alk/Ca means I have to remove 100ml of tank water and replace with RODI to have a net zero effect on salinity

In my case it nicely balances with the average amount I skim out each day and which is topped up by my ATO.

 

[Lavey29]

Well if you're using :

a) Sodium Bicarbonate/Carbonate for Alkalinity; and
b) Calcium Chloride for Calcium.

then:

The coral will take up the Carbonates from (a) and the Calcium from (b) to make Calcium Carbonate skeleton so you're left with Sodium and Chloride (NaCl) which is salt, subsequently increasing salinity over time.

Very interesting and i wasn't disputing your claim just asking how the process occurred.

So every reefer here has a tank that slowly constantly increases salinity over time if they have coral and dose for it.

Really curious if Randy has studied and concluded this also. Thanks for sharing. I was wondering why my salinity was slowly increasing and you may have unraveled the mystery for me. I skim very dry to so don't remove much each week.

 

[fish farmer]

Only 120ltr/30 gal

I have a 29 with sump and big skimmer. If I skim wet and it fills the cup I can have some salinity drifts. I actually have the drain line going back in the sump and I skim dry now. I had a couple of overflow issues when I used epoxy in tank.

 

[gbroadbridge]

Very interesting and i wasn't disputing your claim just asking how the process occurred.

So every reefer here has a tank that slowly constantly increases salinity over time if they have coral and dose for it.

Really curious if Randy has studied and concluded this also. Thanks for sharing. I was wondering why my salinity was slowly increasing and you may have unraveled the mystery for me. I skim very dry to so don't remove much each week.

I just searched and Randy does indeed mention it In this article

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION

There is no aspect of reef aquarium chemistry more important than calcium and alkalinity. Many of my previous articles have described various aspects of these systems in detail. In reading those articles, aquarists will note one pervasive theme: that maintaining appropriate levels of each are...

www.reefedition.com

"The rise in salinity of these products over time can be very roughly calculated, though there are several reasons why this calculation is only an estimate. For every 1000 meq of alkalinity added in this fashion (and the matching amount of calcium) these products will deliver on the order of 60 grams of other ions to the tank. In a tank with a low calcification demand (defined later to be 18.3 thousand meq of alkalinity per year in a 100 gallon tank (0.4 dKH/day)) this effect will raise the salinity by 3 ppt per year (compared to a normal salinity of S ~35). In a high demand tank (defined later to be 219 thousand meq of alkalinity per year in a 100 gallon tank (4.4 dKH/day)), the salinity will rise by 35 ppt in a year, or approximately doubling the salinity. Consequently, the salinity should be monitored closely in using these types of additives, especially in a tank with high calcification rates."

 

[Lavey29]

I just searched and Randy does indeed mention it In this article

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION

There is no aspect of reef aquarium chemistry more important than calcium and alkalinity. Many of my previous articles have described various aspects of these systems in detail. In reading those articles, aquarists will note one pervasive theme: that maintaining appropriate levels of each are...

www.reefedition.com

"The rise in salinity of these products over time can be very roughly calculated, though there are several reasons why this calculation is only an estimate. For every 1000 meq of alkalinity added in this fashion (and the matching amount of calcium) these products will deliver on the order of 60 grams of other ions to the tank. In a tank with a low calcification demand (defined later to be 18.3 thousand meq of alkalinity per year in a 100 gallon tank (0.4 dKH/day)) this effect will raise the salinity by 3 ppt per year (compared to a normal salinity of S ~35). In a high demand tank (defined later to be 219 thousand meq of alkalinity per year in a 100 gallon tank (4.4 dKH/day)), the salinity will rise by 35 ppt in a year, or approximately doubling the salinity. Consequently, the salinity should be monitored closely in using these types of additives, especially in a tank with high calcification rates."

Nice find and so interesting. It fits right into what I'm seeing in a 14 month old tank. I have high calcification rates now because I dose AF Build at night. I've had to increase my calcium dosing slightly also over and above my alk consumption.