How Much Water Actually Gets "Changed"?

[ubiq]

Using Apex's AWC, e.g., since the "new" water is being pumped in at the same time the "old" water is being pumped out, some of the "new" is lost immediately. In a 100g tank set at a 20g daily change, how long would it take to effect an actual 10 percent reduction of, for example, nitrates (assuming no additional nitrates were being added)? How effective are water changes since we don't empty the tank before adding "new water"?

 

[Idech]

I don’t know this tool but it would bother me to be dumping new water as it is poured in. Is there any way to do the WC in 2 different steps ?

 

[KStatefan]

http://reefkeeping.com/issues/2005-10/rhf/index.php

 

[JTP424]

There is also something to be said about location of input and output. Different sides of the tank would decrease the amount of new water being removed.

 

[Gill the 3rd]

Ive used this calculator in the past:

Effective Water Change Calculator

Aquarium calculator; Estimate the effective water change amount of several combined smaller water changes.

www.hamzasreef.com

Edit:

Theres also this one that measures the effect of the water changes for a certain parameter, but I believe the one I posted above applies to your situation

Effect of Water Changes Calculator

Aquarium calculator; Estimate the effect of repeated water changes on the concentration of a given substance.

www.hamzasreef.com

 

[rtparty]

20% daily? That is way too much and a total waste to begin with.

In any AWC setup, you should pull from "upstream" and put the new water in "downstream"

 

[TheBear78]

Unless you've placed the inlet and outlet tubing next to each other it shouldn't be too terrible. And as above, I got the impression that these systems were designed for small changes each day or even a continous slow trickle. The pumps simply won't flow that much.

 

[ukgeoff]

For regular daily water changes, 1 - 2% of tank volume is the guideline to replace daily.

I've just swapped from 15% bi-weekly water changes to smaller daily water changes. For my 100-litre tank, I simply use a jug to remove one litre of tank water each morning and then add one litre of new salt water. Changing one litre of water is so much easier as I don't need to heat the water or mess with heavy buckets.

Using the hamzasreef calculator above, I'm replacing 26.03% of my tank water monthly with a small one-litre daily water change:-

My previous bi-weekly changes of 15% work out at 27.75% water change per month, so the monthly water reduction with small daily changes is pretty small.

I've only recently started daily water changes, so don't know how my tank will adapt to my new regime. However, I'm finding the small daily water changes a lot more convenient and easier, so will most likely swap to this method.

For your 100g tank, a 1-gallon daily water change should suffice.

 

[Randy Holmes-Farley]

For regular daily water changes, 1 - 2% of tank volume is the guideline to replace daily.

I've just swapped from 15% bi-weekly water changes to smaller daily water changes. For my 100-litre tank, I simply use a jug to remove one litre of tank water each morning and then add one litre of new salt water. Changing one litre of water is so much easier as I don't need to heat the water or mess with heavy buckets.

Using the hamzasreef calculator above, I'm replacing 26.03% of my tank water monthly with a small one-litre daily water change:-

My previous bi-weekly changes of 15% work out at 27.75% water change per month, so the monthly water reduction with small daily changes is pretty small.

I've only recently started daily water changes, so don't know how my tank will adapt to my new regime. However, I'm finding the small daily water changes a lot more convenient and easier, so will most likely swap to this method.

For your 100g tank, a 1-gallon daily water change should suffice.

FWIW, I mathematically compare lots of different water change scenarios here:

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

 

[Danny99]

the "new" water is being pumped in at the same time the "old" water is being pumped out

sounds like madness to me, what an unnecessary waste of water

 

[Doctorgori]

just my opinion but small daily changes are a waste mathematically speaking …

edit add: Randy’s article mutes that somewhat

larger weekly 10% or more makes waaaay more sense to me

 

[Troylee]

I see better results with massive water changes every couple weeks.