Help me understand water change % and amount of filtration?

[Masha]

What is the relationship between the amount of filtration in a tank, and the amount of water you need to replace each week?

I'm curious because looking at the aqua advisor calculator, when I experiment by choosing a larger or smaller filter, the message about filtration changes, but the recommended amount of water you need to change does not.

Is that just an aqua advisor glitch? I know this is an automatic tool and probably not super acurate.

 

[GodFan]

What is the relationship between the amount of filtration in a tank, and the amount of water you need to replace each week?

I'm curious because looking at the aqua advisor calculator, when I experiment by choosing a larger or smaller filter, the message about filtration changes, but the recommended amount of water you need to change does not.

Is that just an aqua advisor glitch? I know this is an automatic tool and probably not super acurate.

Ironically most filters no matter what size will do pretty much the same job biologocally (the only exceptions being undersized filter which are jot adaquete and filters with some kind of nitrate eating media). Truth is a bigger filter only helps take out bigger amounts of solid waste and add more oxygen.
So it really wouldnt make a huge difference. If you are wanting to reduce water changes or % of water changed you need to look into live plants and aenorobic bacteria. The bacteria can be achieved with a deep sand bed filter or a fikter media such as seachem matrix.

 

[molliwopp]

A good rule to flow is 4x the volume of the tank in an hour this can be different for dirty fish that produce more waste and heavily stocked tanks which i would suggest 8x.

You mention the calculation of the water you need to change staying the same and thats because at the end of the week the ammonia through to nitrate conversion would remain the same as the nitrate reading would be donated by the amount of ammonia being produced.

Whether your filter can eliminate ammonia faster or slower the nitrate outcome would remain the same.

 

[Masha]

Ironically most filters no matter what size will do pretty much the same job biologocally (the only exceptions being undersized filter which are jot adaquete and filters with some kind of nitrate eating media). Truth is a bigger filter only helps take out bigger amounts of solid waste and add more oxygen.
So it really wouldnt make a huge difference. If you are wanting to reduce water changes or % of water changed you need to look into live plants and aenorobic bacteria. The bacteria can be achieved with a deep sand bed filter or a fikter media such as seachem matrix.

Wow.
Really?

I'm not really looking to reduce the % of water change, more wanting to make super-sure my tank can sustain the amount of fish I want to add.

So for example, I've got a 24 gallon tank with an Aquaclear 30 filter. I was thinking of upgrading to an Aquaclear 70 - which presumably has a lot more capacity for filter medium? I thought that would be the difference - more medium, more BB?

Is the difference between those to filters more the flow than the amount of filter media?

I've got live plants, hopefully will soon have more.

 

[Masha]

A good rule to flow is 4x the volume of the tank in an hour this can be different for dirty fish that produce more waste and heavily stocked tanks which i would suggest 8x.

You mention the calculation of the water you need to change staying the same and thats because at the end of the week the ammonia through to nitrate conversion would remain the same as the nitrate reading would be donated by the amount of ammonia being produced.

Whether your filter can eliminate ammonia faster or slower the nitrate outcome would remain the same.

Ah.

So if I'm understanding this correctly: the amount of ammonia determines the amount of nitrate at the end of the week, so if you have "enough" filtration the water change % stays the same even with a bigger or more powerful filter.

But a more powerful filter helps if you have more (or messier) fish as it brings all that waste in contact with the BB faster and more often, so the conversion itself happens faster - in other words the fish are not exposed to ammonia and nitrates for as long as they might with a weaker filter?

 

[BillD]

No. The bio load determines the need for water changes. You can not have less than 0 ammonia or 0 nitrites. Adding more filtration won't change this or speed it up. The amount of bacteria will be determined by the bioload, not the size or number of filters, assuming a size that is sufficient.The variable is the nitrate, which determines the minimum amount and interval for water changes. However, changing more than the minimum is cheap insurance against problems. It is virtually impossible to change too much water.

 

[Kristian Tombs]

I overkill it soo much:

I have a heavily planted 10 gallon.
I run a 150 gph filter on that 10 gallon.
I change 75% of the water every week in that tank.
It's got more stock than your average ten gallon but there is no problem with water conditions

 

[Masha]

No. The bio load determines the need for water changes. You can not have less than 0 ammonia or 0 nitrites. Adding more filtration won't change this or speed it up. The amount of bacteria will be determined by the bioload, not the size or number of filters, assuming a size that is sufficient.The variable is the nitrate, which determines the minimum amount and interval for water changes. However, changing more than the minimum is cheap insurance against problems. It is virtually impossible to change too much water.

Okay, that makes sense.

Sorry for the repeated questions, just trying to understand.

BB increases in response to the amount of waste. Flow brings the waste in contact with BB, faster. Simply having a bigger filter wont mean more BB as that is determined by the amount of waste. So above a certain size and power, wont make much difference? Assuming the amount of waste stays the same?

What is the difference then between tanks with poor, adequate, and good filtration?

In a poorly filtered tank, there is a lot of waste and not enough space for the amount of BB needed to process it quickly? Maybe not enough flow to get the waste to the BB for fast processing? So in a tank like that, nitrites and ammonia might stay in the water longer?

In an adequately filtered tank - enough BB and flow to ensure that ammo and nitrites stay at 0.

And in a tank with a bigger and more powerful filter - ??

Or is the point basically that you need to aim for "enough" filtration and getting a bigger or more powerful filter is not really going to make a difference?

Sorry if I seem dense - your answers are helping me understand.

 

[molliwopp]

Okay, that makes sense.

Sorry for the repeated questions, just trying to understand.

BB increases in response to the amount of waste. Flow brings the waste in contact with BB, faster. Simply having a bigger filter wont mean more BB as that is determined by the amount of waste. So above a certain size and power, wont make much difference? Assuming the amount of waste stays the same?

What is the difference then between tanks with poor, adequate, and good filtration?

In a poorly filtered tank, there is a lot of waste and not enough space for the amount of BB needed to process it quickly? Maybe not enough flow to get the waste to the BB for fast processing? So in a tank like that, nitrites and ammonia might stay in the water longer?

In an adequately filtered tank - enough BB and flow to ensure that ammo and nitrites stay at 0.

And in a tank with a bigger and more powerful filter - ??

Or is the point basically that you need to aim for "enough" filtration and getting a bigger or more powerful filter is not really going to make a difference?

Sorry if I seem dense - your answers are helping me understand.

Sounds right to me. A bigger/more filtration is going to be better if you want to add more fish. If you ride the filter at the top of its capability, adding more fish or waste is going to push it over the edge where it cant process it faster than its being created. Aiming for adequate filtration for your bioload(i.e waste and toxin production) is always the goal.

The bacteria has to grow to the amount of waste created like you said. Getting a huge filter with afew fish is fine. But whether its a huge filter or not ammonia can spike. Leaving large amounts of food in the tank after feeding will rott and create sudden spikes in ammonia because your filters bacteria has only grown to the current bioload. The smaller filter my struggle to grow more BB to process this. A larger filter wont be able to eliminate it right away but will slowly establish more bacteria to eliminate the extra ammonia.

 

[Masha]

Thanks Molliwopp

I hope I understand now.

Still wondering if I should upgrade from an aquaclear 30 - according to the aquarium advisor, that should give me plenty of filtration for the fish load I want.

Getting paid again soon, might just spend the money on that instead of, you know, rent and food

 

[GodFan]

Honestly I wouldnt upgrade unless you have an issue with water clarity. Thats all a higger filter will do for you is remove chunks and such faster. Probably the simplest way to say it is a bigger filter offers more mechanical filtration but not biological.

 

[Masha]

Honestly I wouldnt upgrade unless you have an issue with water clarity. Thats all a higger filter will do for you is remove chunks and such faster. Probably the simplest way to say it is a bigger filter offers more mechanical filtration but not biological.

I've got very few fish in my tank at the moment, so no problems with my filter that I know of. But I'd like to add more and am worried that my current filter is not good enough.

According to the aquarium advisor, I should upgrade if I add the number of fish I'd like. But I know it's not all that accurate?

 

[BillD]

Another consideration is that every hard surface in the tank can support BB if there is enough food for them. When food increases their numbers will increase.

 

[molliwopp]

As the filtration is the backbone of any stable aquarium enviroment it isnt the place to skimp on, i would suggest getting the best you can in your budget.