Math question.

[mbmikebray]

90g with 30g sump so approx 100g.
Trying to keep sg at 1.025. Have added salt mix to top off - approx 12g container so difficult to know how much salt to add. When sg drops slightly below 1.025 I add more to get back to target .
If I add 10g at 1.028 and do this 10% water change how much would it raise the total in the tank? Is this ok to add, have always added to top off - thought it might be easir to add at water change. How do people do this accurately if no ato?
Obviously the skimmer cup takes salt out over a period of time, I also take water out to dip coral etc and when siphoning water to acclimate new coral/livestock.
I never let the sg drop to 1.024 so only small adjusment needed.

 

[sorinwilcox]

I would say it is worth the ato no mater what. As you would have to consider heat and temp.

I would definitely say it is worth even if you get the 3d printed ato with a water bottle.

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[mbmikebray]

Sorinwilcox

Thank you for your reply however I think you have missunderstood my question.

 

[Vinny Kreyling]

Mike,
Removing water & skimming should not affect salinity, it's full strength water.
I would try make up @ 1.026 since you claim a minor variation & go from there.
Salinity can be DROPPED immediately with -0- affect. However raising it should be done slowly. Therefore my recommendation.

 

[dubmaneh]

Minor fluctuations in salinity over time are ok. I make adjustments if needed when I do water changes. For 10% WC, I make the new water slightly higher or lower to get to where I need to be.

I believe the formula you are looking for is something like this:

(new water salinity - current salinity) x % of water changed = change in system salinity

Ex: (1.028-1.024) x .10 = 0.0004 change in system salinity.


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[mbmikebray]

Vinnie,
I was thinking that the water in the skimmer cup is being replaced with rodi water via the ato, therefore over time reducing the sg value, also any water removed for any other purpose results in the same scenario happening...It does drop over a period of weeks as I wet skim most of the time to reduce the odour in the sump from the skimmer cup..
Thank you for your reccomendation re raising the sg.

 

[mbmikebray]

Dudmaneh,
So it appears a small increase or reduction to the sg added during a 10% change results in a very small reduction/increase of the sg in the system. Not enough to affect any of the livestock.
Like Vinnie suggested I will add 1.026. I will do this on a regular basis and test also to maybe keep the sg at 1.025
I am not suggesting anyone else should do this!

 

[kurt_n]

Vinny is saying that the skimmer doesn't suck out salt water... skimmed water is pure water, not salt water. So any water from the ATO that replaces it doesn't affect salinity at all.

I think the equation you're looking for is...

Final SG = [(SG1 x gallons1) + (SG2 x gallons2)]/(gallons1 + gallons2)

 

[Member No. 1]

Vinny is saying that the skimmer doesn't suck out salt water... skimmed water is pure water, not salt water. So any water from the ATO that replaces it doesn't affect salinity at all.

I think the equation you're looking for is...

Final SG = [(SG1 x gallons1) + (SG2 x gallons2)]/(gallons1 + gallons2)

Kurt, with all due respect, if a person is wet skimming, how is that pure water?

 

[kurt_n]

Kurt, with all due respect, if a person is wet skimming, how is that pure water?

Sorry... yes... if wet skimming, then the skimmate is probably close to the tank salinity.

I missed the comment about wet skimming in the OP's response to the response I was talking about.

Here's a good read: http://reefkeeping.com/issues/2006-08/rhf/index.php#6

 

[Vinny Kreyling]

Kurt, Perhaps not the best way of saying it but full strength water in a saltwater system is whatever the salinity is. In no way did I mean skimate is fresh water, to me that is a ridiculous statement.
I read the article & it also reminds us skimate is in fact salt water.

 

[mbmikebray]

The reason I wet skim to reduce the odour in the sump is the possible effect on the ph in the system. The odour from the cup is very 'dense' if that's the right word to use and the air inlet into the skimmer is not far from the top of the skimmer cup where it 'vents' into the sump. I have attaced a hose to the air inlet so it is further away from the cup to try reduce the above to some extent. I would extend this out of a window as I have read some people do this however there is not a window at this side of the room. (Condo)
One other benefit in my experiece of wet skimming is the reduction of the odour when opening the sump. I wet skim approximately 16 oz per day.
Thank you for all replies, interesting conversation...

 

[Sk8r]

It's 1/2 kitchen measuring cup whacked on counter until contents level)cup dry ocean salt in every gallon of ro.di water, so if you need 12 gallons of salt water, get a 23 gallon trash can from Amazon and mix in that, 12 gallons of water with 6 cups of salt: mix at least 8 hours before use to get fully dissolved.

Getting an ato does not mean getting a doser. You can rig one with any small electric float switch. Just stick the float switch to your tank and run a line to a small pump in a few gallons of fresh water (ro/di) and cease to worry about your salinity. It will continually top off at the rate of an eighth of a cup of fresh water, and your salinity will stay optimum. The DIY forum should be able to walk you through construction of a DIY ATO for minimal cost and maximum effect.