Water change question

  • We are currently upgrading MFK. thanks! -neo

Pond9

Plecostomus
MFK Member
Feb 9, 2017
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I normally do 80% change once a week on all my tanks. Would doing a 30% change one day a week and a 50% one day a week so 30% wed and 50% sat be better than one 80% a week? My nitrates are 40ppm at highest on my tanks at 80% a week. Usually between 20-30 depends on the feedings.
 
No. A single 80% water changes will keep your nitrate at lower levels than a 50% and a 30% each week. To simplify, a 50% and 30% is the same as two 40% water changes per week.

With 80% weekly water changes, nitrate will range between 10 - 50 ppm between changes with an average of 30 ppm with 40 ppm weekly nitrate accumulation.

With two 40% water changes/week, nitrate will range between 30 - 50 ppm between changes with an average of 40 ppm with 40 ppm weekly nitrate accumulation.
 
Thanks, I think I will do one 30% wed and a 80% sat still then. If I could do 30% daily I would but my wife would not be thrilled lol
 
Thanks, I think I will do one 30% wed and a 80% sat still then. If I could do 30% daily I would but my wife would not be thrilled lol

Include the wife in your water change activities. If she feels part of what you're doing then it's all good to them, you know, doing stuff together and all that. Before you know it your wife will be doing your water changes whilst you have your feet up watching the game. Happy days.
 
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Include the wife in your water change activities. If she feels part of what you're doing then it's all good to them, you know, doing stuff together and all that. Before you know it your wife will be doing your water changes whilst you have your feet up watching the game. Happy days.
She's mad about the water bill lol. She seldom looks at the fish.
 
I see.

I'm not saying your bill is the same.....

...but my water bill is MOSTLY not water. Indeed, 80% is garbage, recycles, sewer, and storm drain, and even the part that is water, includes a fixed part for the meter that has nothing to do with actual water usage.

If I used no water at all --- zero --- my bill would be reduced by 20%, or basically the price of two fully loaded Subway meals.

So my 17,000 gallons cost me $25. An extra 57 gallons a day (water changes) would cost me $2.50 per month.


Sorry, ex-accountant. That's the way we look at bills.
 
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I see.

I'm not saying your bill is the same.....

...but my water bill is MOSTLY not water. Indeed, 80% is garbage, recycles, sewer, and storm drain, and even the part that is water, includes a fixed part for the meter that has nothing to do with actual water usage.

If I used no water at all --- zero --- my bill would be reduced by 20%, or basically the price of two fully loaded Subway meals.

So my 17,000 gallons cost me $25. An extra 57 gallons a day (water changes) would cost me $2.50 per month.


Sorry, ex-accountant. That's the way we look at bills.
My father wanted to be an accountant I felt the same way lol. Our water bill was $200+ but we have a pool and I take long showers I work in the die trade takes lots of hot water to take off grease and dust. She complained to me while I was water changing that I used to much water (only 4 tanks total about 500 gallons total) I said at absolutely worse its 5 bucks a month
 
Since Im going on vacation tomorrow, ive been doing 30 gallons per day on my 240 for the past week and a half. Only have two fish in there. But yeah that's what I also wondered, if there is difference between a couple smaller ones per week, or one large one
 
There is.

  • Perform a 30% water change followed by a 50% water you are changing 65% of the original water.
  • Perform a pair of 40% water change and you are changing 64% of the original water.
  • Perform an 80% water change and you are changing 80% of the original water.
This is an oversimplification because technically whatever you are trying to remove from the water is being added in the intervening days but the general idea is that one large water change removes more than two smaller ones.

Of course, you have to balance this with how sensitive your fish are and how different the incoming water is from the outgoing.
 
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