Calculating auto water changes

[clevername]

Hey all, needs some help/clarification.

Im working with this online calculator that figures out how much a water change reduces a substance in the tank (Alk, Cal, Nitrates....ect)

https://www.hamzasreef.com/Contents/Calculators/EffectOfWaterChanges.php

The results im getting cant be right??

Examplein order of the fields inputted on the website)

50 Gallon tank
2.5 gallon water change
30 water changes (this will represent 30 separate days)
10 DKH (Initial concentration: i have perfect water :hmm5: )
-1 DKH (showing the amount of DKH used per day)
10 DKH (the Concentration in Make-Up Water)

shows after 14 days ill be down to 0.8 DKH. Which i know this isnt EXACTLY accurate because of buffering effects. The point is, how can 5% (2.5 gallon) water change DAILY not keep up with that 1 dkh drop.

 

[huff747]

If 50 gallons of water dropped 1DKH in a day, pulling out 2.5 gallons of the water which is now at 9DKH and adding 2.5 gallons of new water at 10DKH isn't going to bring the remaining 47.5 gallons which are still at 9DKH back up to 10DKH. That 2.5 gallons of new water would have to be much higher in order to bring up the other 47.5 gallons.

 

[huff747]

According to the calculator the new water would have to be 29dkh for the 2.5 gallon water change to keep the overall dkh at 10.

Although I don't know what you're plans are but you may be overthinking this a bit. Are you planning to use kalk in your ATO, 2 part, or a calcium reactor? Or were you wanting water changes to handle it all?

 

[clevername]

ok you got me, definitely over thinking it. I do have dosers for alk and cal which work fine.
so heres what i should have started with.

im setting up a 210g and finally have an automatic water changer. No way can i keep up with alk and calcium swings with water changes alone. (i knew it would cost too much BUT looks like you were right and the math just doesn't support it)
So the question is, is automatic water changes truly just for keeping trace elements in check?

Iv been running a 50 gallon for years and RARELY (maybe do monthly water changes; as i dose red sea's trace elements per package instructions). I say that because iv never had issues with nitrates, which i assume is also the point of a water change.

i know i might be leading myself into the triton method but im now trying to figure out how much i should be auto water changing a day (percentage wise).

 

[huff747]

I probably don't have a great answer. I think there are a lot of reasons people set up AWC. I started doing them in part because where the tank is now set up is on the other side of the wall from my water station so it was very close and very easy. My old tank was on a different floor and on nearly the opposite side of the house so the only choice was lugging buckets. So part of the reason I set up AWC is because I finally could. The other reason I did is even though they're small, it's pulling some old water out which surely has stuff I don't want hanging around, and adding new fresh water and I figure there has to be some good in that.

At least in my own mind (placebo effect?) it's doing some form of cleaning the tank a bit each day. And what I may spend on extra salt, I'm not spending on ICP tests and Triton additives (not that there is anything wrong with that, I also don't have a fuge big enough to do Triton) and I am pretty happy with how things are going so I'm not going to tinker.

 

[Pife]

As much as you want to. That being said I typically do about 50 gallons a week on my total gallons of about 430. I do automated constant water changes with my liter meter.

 

[clevername]

I probably don't have a great answer. I think there are a lot of reasons people set up AWC. I started doing them in part because where the tank is now set up is on the other side of the wall from my water station so it was very close and very easy. My old tank was on a different floor and on nearly the opposite side of the house so the only choice was lugging buckets. So part of the reason I set up AWC is because I finally could. The other reason I did is even though they're small, it's pulling some old water out which surely has stuff I don't want hanging around, and adding new fresh water and I figure there has to be some good in that.

At least in my own mind (placebo effect?) it's doing some form of cleaning the tank a bit each day. And what I may spend on extra salt, I'm not spending on ICP tests and Triton additives (not that there is anything wrong with that, I also don't have a fuge big enough to do Triton) and I am pretty happy with how things are going so I'm not going to tinker.

This pretty much sums it up for me too. Trying to not break the bank monthly on water changes BUT still have a positive effect. 10% a week is my goal too, over 7 days.