Filter gallon ratings

[threecharacters]

I have a Danner Ovation 380 internal filter on my 20 gallon long. The filter is rated at 100 gph which is suitable for up to a 25 gallon tank using the 4x volume turnover benchmark. In my own personal opinion, the flow from this filter seems pretty good. Better than some similar rated filters I've owned over the years.

The tank is currently stocked with 7 Pristella tetras and 7 Cardinal tetras. I'd like to stock the tank more. However, according to aqadvisor, the tank is 64% stocked with only filtration of 106%. If I stock more, it says the filtration is inadequate. Apparently aqadvisor de-rates all the filters to 65% of the manufacturers rating. They say this is based on experience, typically manufacturers overstate the capabilities of their filters.

However, I am dubious of the legitimacy of this. For example, I have a single sponge filter on my other 20 long thats rated to 40 gallons, but the sponge filter has a much lower turnover rate. I would be surprised if it even did 20 gph. Still aqadvisor would say this is more than enough filtration for this tank.

Do you think the Danner internal filter is sufficient, and I can add to the tanks stocking?

 

[PheonixKingZ]

Aquadivisor isn’t always accurate, so be careful what you trust...

Do you have a link/picture for the filter in question?

 

[threecharacters]

I have a photo of the tank. Honestly, the filter does look kinda small in the tank. I also really need to move the Java fern elsewhere... I prefer when the tank hardware is small and understated. If I have to I have a HOB filter in storage I could get out. This tank was recently a 10 gallon that I upgraded to a 20 long in order to move the Cardinal Tetras in my other tank into this tank. The filter felt like more than enough for the 10 gallon, but maybe it's too small for the 20 gallon?

 

[PheonixKingZ]

I can’t tell, is that an internal filter? I really need a brand or model number or something, so I can look it up.

 

[threecharacters]

It's a Danner Ovation 380 internal filter. I mentioned it in the original post.

 

[Jamesthecat]

Aquaadvisor base their flow rates on about 67% of the manufacturers stated gph. Its very subjective and is affected by contents of the tank ie. rock & plants also filter media types will change the flow rate.

Practical Fishkeeping did a comparison a while ago that you can look up but the numbers on the box can be wildly different from actual flow.

Ive stuck a pc flow meter on the output of my Eheim to monitor the gph

 

[Fishmar]

For that tank, if you put a sponge filter on the other side of the tank i am sure that the combined filtration would be sufficient.
You could also put a small HOB filter on the right side as well, something like an aquaclear 30. Just my opinion. Tank looks good! Take that floating rhizome and stick it between the rocks lol

 

[mcordelia]

Very pretty tank! To complicate the filtration question, not all kinds of "overstocking" are the same either. I think overstocking with tetras is a lot more benign than trying to overstock with "messy" species like goldfish or plecos or large cichlids etc. I think a good benchmark to go for of overstocking is 10x using manufacturers numbers, but it also depends on the filter itself. Some manufacturers are more truthful in their flow ratings than others. Bottom like, I don't think you can go wrong with adding more filtration (until your tank becomes a whirlpool, then it might be a bit much ), but I also think that you will be able to gauge how things are going before they crash if you think you are "close" to what you need. If you up the stock gradually and start seeing repeated blooms or an increase in algae etc, then it's likely that you need to increase the bacterial filtration/plants.

 

[Essjay]

Filter flow also depends on the species of fish. Those species which come from fast flowing rivers prefer a high water flow, but those fish which come from slow moving rivers or lakes do not like a lot of water flow. Buying a filter with a large turnover for these fish is pointless as you'd only have to turn the flow down.

 

[Utar]

My take is when in doubt filtrate, when in doubt of that filtrate then filtrate some more.

Filter manufacturers measure the flow rate of their filters empty and right at the head of the flow. So with media and filtration added it is a best bet to cut the manufactures measured flow rate in half. Not all filters are equal even those of the same make and model can be different depending on the manufactures quality control methods.

It is much better to over filtrate then run the risk of under filtrate. My 55 has a canister rated for 793 gph, half that is 396 gph. I also have a double sponge filter and a power head with an attachment that filters the water. So I have no doubt that I am getting more then I need for filtration in my 55 gallon tank.

So get your HOB out of storage and filtrate with every thing you got.

 

[threecharacters]

For that tank, if you put a sponge filter on the other side of the tank i am sure that the combined filtration would be sufficient.
You could also put a small HOB filter on the right side as well, something like an aquaclear 30. Just my opinion. Tank looks good! Take that floating rhizome and stick it between the rocks lol

The Java Fern isn't really supposed to be in there. I just don't have another place to keep it for the time being. Maybe I'll put it in a vase.

For better or worse, I picked up two splash tetras (Copella sp.) and a dwarf crayfish yesterday. The splash tetras are unidentified, but I think they're different species. They came in different shipments, and one was bycatch from a Iguanodectes geisleri shipment. I'll monitor it closely, and if things look strained I'll add the other filter. There's a good change I'll add the HOB I have in the next few days.