Which is more effective NO3 Dilution Rate?

[Super Fly]

I've been doing water changes by adding 15 gals of clean water to sump & after letting water circulate throughout the system for 10mins, remove 15 gals of water via manifold. Recently I read online that it's more effective to first drain 15 gal of dirty tank water into the container with clean water, let that mix and then add back 15 gal of now NO3 diluted water into tank. Been trying to google dilution calculator to learn which method is more effective at lowering NO3 but can't figure out how to use the dilution formula... this is way above my pay grade . Or would both methods dilute NO3 at same rate? Can any chemists out there please enlighten me? thx

 

[lapin]

Perplexed: it is better to drain 15 gallons of dirty tank water and replace it with fresh mixed.

 

[Miller535]

Why are you doing it this way? So that you don't have to shut your pumps off?

 

[Miller535]

The way you are doing it, you are dumping out some of the clean water you just put in. I don't understand why

 

[Super Fly]

Perplexed: it is better to drain 15 gallons of dirty tank water and replace it with fresh fresh mixed.

That's what I thought as well, but according to the online post it's more effective to drain 15 gal to container w clean water, let them mix and then return 15 gal into tank...

Why are you doing it this way? So that you don't have to shut your pumps off?

Pump remains on. It's just so much easier and less messy this way then having to stick my hand into DT with drain hose and having to create siphon. I just take the manifold hose w valve and drain into bucket.

 

[Miller535]

That's what I thought as well, but according to the online post it's more effective to drain 15 gal to container w clean water, let them mix and then return 15 gal into tank...
Pump remains on. It's just so much easier and less messy this way then having to stick my hand into DT with drain hose and having to create siphon. I just take the manifold hose w valve and drain into bucket.

I get what you are saying. Buy a cheap pump and put it in your sump, or leave it in your sump and use it to pump water out with then. You are wasting part of your water change by adding clean water then pumping it back out.

If you really want to dilute, you make the biggest batch of water you can, lets say thats 30 gallons. Dump 30 gallons out and replace with 30 gallons. The more you take out at one time, then replace the more you will drop nitrate. Say your tank is 60 gallons. If you dump 30 and replace with 30 you should cut your nitrate in half, your way it will only be a quarter.

 

[Super Fly]

I get what you are saying. Buy a cheap pump and put it in your sump, or leave it in your sump and use it to pump water out with then. You are wasting part of your water change by adding clean water then pumping it back out.

If you really want to dilute, you make the biggest batch of water you can, lets say thats 30 gallons. Dump 30 gallons out and replace with 30 gallons. The more you take out at one time, then replace the more you will drop nitrate. Say your tank is 60 gallons. If you dump 30 and replace with 30 you should cut your nitrate in half, your way it will only be a quarter.

That's what majority of us think and I did too but this online post & possibly chemistry says it's more effective the other way. Thus my reason for trying to use a dilution calculator to resolve this but I can't figure out how, it's just too scientific for my old brain. ;Dead So asking any chemists out there to chime in.

 

[DarkSky]

This just seems like unnecessarily wasting freshly mixed clean water and time for the sake of not lowering your nitrates as much.

Just do smaller water changes to achieve the same effect and don't worry about which inefficient method you're currently doing or thinking about doing is more effective.

 

[Miller535]

That's what majority of us think and I did too but this online post & possibly chemistry says it's more effective the other way. Thus my reason for trying to use a dilution calculator to resolve this but I can't figure out how, it's just too scientific for my old brain. ;Dead So asking any chemists out there to chime in.

Mathmaetics says that's not true

 

[Super Fly]

Mathmaetics says that's not true

That's the type of confirmation I was looking for, thanks!

 

[Deep dive coral]

That's the type of confirmation I was looking for, thanks!

Can you post original article and the calculator. I can take a look into it.

 

[Super Fly]

Can you post original article and the calculator. I can take a look into it.

Sure thing & thanks.
Here's the article instruction:
"Example from my 55-gallon Reef : Make up 20 gallons of fresh saltwater in a trashcan in front of your tank. Drain 10 gallons of tank water into the 20 gallons of new water, and let that mix. Pump 10 gallons of that water back into your tank, and let the power heads mix that water up in your tank for a minute or so. Then repeat this three more times. Dispose of the now polluted 20 gallons of water. Make up another 20 gallons of fresh saltwater, and repeat this procedure. As long as your temperature and salinity match the tank, your inhabitants won’t be affected adversely, and with each rotation of water, the nitrates are being diluted and removed from your tank.

Simply pulling out all of the water in one massive water change puts stress on your entire tank. Doing small water changes consistently won’t bring nitrate levels down. At best, it will maintain them at their current levels. Using the example above, a tank that was at 80ppm would be around 30ppm after a couple of hours work and your population will be happy and unaffected."

As far as dilution calculator, I found this one http://www.endmemo.com/bio/dilution.php but had no idea how to use it.

 

[Deep dive coral]

I dont think the calculator is working. Nothing g is computing whe. I plug in my numbers. Also do daily or continuous WC according to the math is better then doing 1 massive change.

 

[YankeeTankee]

Let me explain what I think it is you are getting at but preface this by saying the end result is not much different. However what you're saying does have some truth to it. I'll try and word this a few different ways so forgive my repetitiveness I'm just hoping one of the ways of saying it catches, and we'll talk in nitrate terms but it's true for phos/other as well.

A. When you add first, that 15 gallons containing 0 nitrate mixes with tank water thereby diluting nitrate (lowering it). Then when you remove 15 gallons, you will be removing a small portion of that 0 nitrate water you just added. So you're removing the water with diluted nitrate. Explained a third way and more crude way, you just made your water cleaner and now your getting rid of a portion of that cleaner water.

B. When you remove first, all of the water you subsequently add with 0 nitrate remains in the tanks. You did not remove a portion of the clean water.

 

[Dan_P]

I've been doing water changes by adding 15 gals of clean water to sump & after letting water circulate throughout the system for 10mins, remove 15 gals of water via manifold. Recently I read online that it's more effective to first drain 15 gal of dirty tank water into the container with clean water, let that mix and then add back 15 gal of now NO3 diluted water into tank. Been trying to google dilution calculator to learn which method is more effective at lowering NO3 but can't figure out how to use the dilution formula... this is way above my pay grade . Or would both methods dilute NO3 at same rate? Can any chemists out there please enlighten me? thx

Your way produces the following dilution

original nitrate level x system volume / (system volume + 15)

The slightly better way produces this dilution

original nitrate level x (system volume - 15) / system volume

If you plug in your numbers, you will find a small advantage doing it the “better” way.

 

[Super Fly]

Your way produces the following dilution

original nitrate level x system volume / (system volume + 15)

The slightly better way produces this dilution

original nitrate level x (system volume - 15) / system volume

If you plug in your numbers, you will find a small advantage doing it the “better” way.

Finally a dilution calculation reply, appreciate it!

 

[Miller535]

I did not realize you meant to do your method multiple times in the same day. I would agree that to some extent it would work. And probably would be less of a shock on a system. But i still contend that just doing a standard water change is going to remove more nitrates. I have always personally had the same opinion as Mark Levenson. That as long as you match your new water to your tank, ie, mag, calcium, alk, temp, and salinity, you can do as big of a water change as you'd like. The only exception to this would be maybe if your nitrates or phosphates were super high and you changed a large portion of the water.

 

[Miller535]

Also I am not sure if you are familiar with hams reef, but he has TONS of very helpful calculators. You may find this calculator useful, I don't know.

Effective Water Change Calculator

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

www.hamzasreef.com

 

[Randy Holmes-Farley]

That's what majority of us think and I did too but this online post & possibly chemistry says it's more effective the other way. Thus my reason for trying to use a dilution calculator to resolve this but I can't figure out how, it's just too scientific for my old brain. ;Dead So asking any chemists out there to chime in.

Chemistry says exactly that removing dirty water and adding clean water is the most efficient for any size change, but when the change is small, the difference is small.

 

[Randy Holmes-Farley]

I show the effect of different ways of doing water changes here:

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