This got me thinking... so i wanna know what u all think lol

[giar]

Assume :
- you have 300 gal tank with 150 gal sump.
- you leave 10cm space from the surface level to the lid.
- you calculate u only have 280 gal of water in your display tank.
- you estimate your 150 gal sump only have 70 gal water and 50 gal media.

Question- when you say you do 50% water change, how much water you should actually need to take out?

 

[esoxlucius]

Anybody who has this pretend set you mentioned can't possibly do an "exact" water change of 40 or 50 or 75% or whatever. The factors you mention, and i'll add water displacement of substrate and decor as well, simply mean you'd have to do some pretty complicated calculations to find out your exact water volume down to the exact gallon. I'm sure most of us aren't that clever so i'm betting that everybody does it my way. That is, at water change time to just simply empty your display tank down to a given level and fill it back up with new water. On my set up i'd say i'm around the 60-70% area give or take but i couldn't possibly give an exact %. My tested parameters show me it's working well. Every once in a while i'll empty out a bit more, at a guess giving me a 70-80% water change. This as a precaution just in case i've had a bit of nitrate creep.

 

[giar]

Yea when i say i do 50% wc is 50% of the display tank.

But shouldnt it be 50% of the entire system?

So it got me thinking, have i been saying the wrong thing when i say i do 50% wc?

 

[giar]

Why i say it should be 50% of the entire system?.. because when u add water conditioner let say u use seachem prime, i suppose u add 9 caps of prime to treat 450 gal system, and not just 300 gal display tank?

*This applies only when u add water directly to the tank

 

[giar]

Ur sump and ur main tank is one system.

Another scenario is when u are treating ur tank with a medicine.

Some meds say "X" amount of med to treat "Y" amount of gallon of water.

In this case, which volume do i need to refer for the amount of medicine i need to add?

 

[Drstrangelove]

Interesting, but maybe a bit of over analyzing.

The goal of a WC, of dechorination, of meds, is to hit a target water chemical level.

Eg., low nitrates, no chlorine/chloramine, proper ppm of meds.

There is no target % for these. The additions and changes must be what is required to hit the target, not an arbitrary dosage or %.

 

[giar]

Ok i will take a common med, prazipro to treat flukes for this discussion.

The recommended dosage is 1 teaspoon per 20gal of water.

A - My water in the display is 280 gal. My water in the sump is 70 gal. Total 350 gal.

B- My display tank volume is 300 gal, my sump volume is 150 gal. Total 450 gal.

C - My display tank is 300 gal.

D - My water in the display tank is 280 gal

Question.
Which volume do i need to refer to dosage the prazipro? A, B, C, or D??. Because it will determine how many teaspoon of prazipro i need to add. And ur answer is?.

 

[TonyS20]

Ok i will take a common med, prazipro to treat flukes for this discussion.

The recommended dosage is 1 teaspoon per 20gal of water.

A - My water in the display is 280 gal. My water in the sump is 70 gal. Total 350 gal.

B- My display tank volume is 300 gal, my sump volume is 150 gal. Total 450 gal.

C - My display tank is 300 gal.

D - My water in the display tank is 280 gal

Question.
Which volume do i need to refer to dosage the prazipro? A, B, C, or D??. Because it will determine how many teaspoon of prazipro i need to add. And ur answer is?.

I've always gone with B when treating with medications. Technically you are putting more than you need into the aquarium but I've never had a problem and complicating things isn't my goal with fish keeping.

If you want the most precise method then you should go with A. When treating with meds you need to add enough to cover the TOTAL volume of water in your system, aquarium + sump = amount of water dose with the medication.

 

[giar]

Not to complicate things, just wanna discuss how things should be done ..

 

[TonyS20]

Not to complicate things, just wanna discuss how things should be done.

Just think about it.

On the label, it says to treat x amount of medication with x amount of aquarium water. If you have a tank 280g and a sump 70g and you only added enough med to cover the main tank, 280g then you would clearly be under dosing the medication.

Volume of water in tank + sump = How much to add

I'm sure that most of us here do not take gravel/rock displacement into consideration when dosing medication as the small amount of water volume this takes up in a 300g system is not enough to cause problems in a freshwater system.

If the medication says to measure out with a teaspoon, then i wouldn't care about adding a little more or a little less than needed. Because a teaspoon will never be a accurate measurement considering teaspoons vary in volume. If it really mattered if you added a little more or less then they would instruct you to measure out the medication with a supplied syringe.