[pogre]

Greetings!

Right now I have an underpopulated mbuna tank that I am waiting on some fish from my LFS I ordered.

I have a 120 gallon high tank (48x24x24).

My question:

For water changes I am taking out and then adding 5 gallons two out of every three days. Is there a problem with this schedule? Does the 10-20% water exchange per week have to take place all at once to be effective?

Everything is great with my water right now, but as I said the tank is fairly underpopulated currently.

Thanks for your help.

 

[SonsOfLeda]

I actually did a fun little Excel chart to answer this question.

After eight weeks of water changes, here are the results:
* 5gal changes 2 of 3 days: 23.81gal of oldest water still remaining (assuming you followed a 2 on/1 off schedule)
* 10% weekly changes: 51.66gal of oldest water still remaining
* 20% weekly changes: 20.13gal of oldest water still remaining

Your way is technically a little bit less effective than doing a 20% weekly water change, but not by a whole bunch. Honestly, the best schedule for water changes is one that you can commit to.

Hope this helps!

EDIT: More fun facts!
* 10% Weekly Changes: ~44 weeks to have only 1% of oldest tank water left
* 20% Weekly Changes: ~21 weeks to have only 1% of the oldest tank water left
* 5gal 2 of 3 Days Changes: ~23 weeks to have only 1% of the oldest tank water left

 

[GTZ]

The longer it takes to change 'x' percentage of water will decrease the effectiveness of water changes in general.

 

[Kanorin]

Best way to tell if your water exchange schedule is good is to test for nitrates. Test just after an exchange, and then test again just before your next exchange.

 

[SonsOfLeda]

Best way to tell if your water exchange schedule is good is to test for nitrates. Test just after an exchange, and then test again just before your next exchange.

To that point, being below 20ppm is a good goal when it comes to nitrates.

 

[pogre]

Thank you so much for the replies. This schedule is most convenient for me right now, but I will keep a close eye on nitrates as I add fish.

I cannot seem to edit my first post, but the dimensions are actually (60x18x24) and it is a 125 gallon tank.