Canister filter = "nitrate factory"? Not anymore!

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ScubaSkeets

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Hi folks!
So I know alot, if not most, people do not like canister filters because they have a reputation for being nitrate factories. So, I got to thinking, why is a canister filter considered a nitrate factory, but a sump is not? Gunk build up inside the canister.
Why doesn't gunk build up inside a sump? Filter socks.
So, I built an inline filter sock compartment that filters out all of the gunk BEFORE it gets inside the canister! I just connected it and it runs great! I guess only time will tell if it helps mitigate nitrate build-up.
20210209_175714.jpg

Just wanted to share!
 
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canister filters can be great if maintained regularly and properly. sump is preferred as it can be managed easily.
canister filters are great for running specialty media like purigen for organic waste, phosguard(not GFO) for silicates and phosphates and carbon for general purity. some come with UV lamps for algae control. they are cumbersome to clean so ppl don't like to clean them often causing accumulation of detritus that starts breaking down over time and become the nutrient factories.
as for your pre-filter. it will get clogged way too easily and more often.
 
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canister filters can be great if maintained regularly and properly. sump is preferred as it can be managed easily.
canister filters are great for running specialty media like purigen for organic waste, phosguard(not GFO) for silicates and phosphates and carbon for general purity. some come with UV lamps for algae control. they are cumbersome to clean so ppl don't like to clean them often causing accumulation of detritus that starts breaking down over time and become the nutrient factories.
Yeah. The accumulation of detritus is what I'm hoping to solve with this. Ill just have to change the filter sock like one does with a sump.
I've also noticed a number of threads that talk about having high nitrates, presumably with a sump. So either a sump is not necessarily a cure-all for nitrate mitigation, or the nitrates would even much more higher with a canister.
 
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DaddyFish

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Is that an FX? filter I see in the photo??? If it's a FX4 or FX6 then I definitely agree with the above comments about the prefilter being too small.
The prefilters on my canisters are built-in and easily removable for cleaning (Oase Biomaster), about 4x the size of what you have pictured, and running on 90-gal tanks. They require cleaning 1-2 times per week.
 

MERKEY

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Great idea!

I ran a fx6 for a while before we upgraded and I ended up just getting the whole thing and filling it with phosgaurd and polyfilter.

Cleaned weekly you won't have an issue.

I can not speak to the pre-filter but you definitely don't want that clogging;)
 
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Sam816

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you will benefit more from having a RO canister with filter floss as a pre-filter. get a see-through one like you have now.
 
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ScubaSkeets

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your pre-filter is very small. it will get clogged way too quickly n choke the whole system. i am afraid you might end up burning the motor in the canister filter when it will run dry.
Is that an FX? filter I see in the photo??? If it's a FX4 or FX6 then I definitely agree with the above comments about the prefilter being too small.
The prefilters on my canisters are built-in and easily removable for cleaning (Oase Biomaster), about 4x the size of what you have pictured, and running on 90-gal tanks. They require cleaning 1-2 times per week.
Ugghh.. I didn't think of it being too small. I figured the flow would basically be the same as without it. The clogging wasn't necessarily a concern because I was planning on cleaning/replacing the socks on regular basis. I was thinking even if the debris did build up in the sock, the flow would still be maintained as the water would exit the sock prior to the build up, no?
 
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DaddyFish

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Ugghh.. I didn't think of it being to small. I figured the flow would basically be the same as without it. The clogging wasn't necessarily a concern because I was planning on cleaning/replacing the socks on regular basis. I was thinking even if the debris did build up in the sock, the flow would still be maintained as the water would exit the sock prior to the build up, no?
A prefilter is a great idea. Don't give up. Just make sure you have a way for maintenance sake, to bypass the prefilter or shut off both sides of the flow without losing prime/syphon. Purging the circuit on any closed loop filtration system is a pain. Don't go there.

As for size/capacity of the prefilter, it needs to be large enough to support running for one week without more than a 25% reduction in flow due to buildup. And you need to be prepared to remove it and clean it at least once each week to avoid decomposition (and eventual nitrate production) from what it's filtering out.
 
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ScubaSkeets

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A prefilter is a great idea. Don't give up. Just make sure you have a way for maintenance sake, to bypass the prefilter or shut off both sides of the flow without losing prime/syphon. Purging the circuit on any closed loop filtration system is a pain. Don't go there.

As for size/capacity of the prefilter, it needs to be large enough to support running for one week without more than a 25% reduction in flow due to buildup. And you need to be prepared to remove it and clean it at least once each week to avoid decomposition (and eventual nitrate production) from what it's filtering out.
It has a valve prior to the prefilter and another one prior to the canister. I dont anticipate it being very difficult to change out the sock. The FX6 is self priming and very easy to get flow going.
 

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It has a valve prior to the prefilter and another one prior to the canister. I dont anticipate it being very difficult to change out the sock. The FX6 is self priming and very easy to get flow going.
Sounds good.
On a side note, if you haven't figured out the trick for purging FX filters before taking them offline for cleaning, shoot me a PM and I will explain in detail.
 

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Check out my build thread that I just started where I talk about how I optimised my canister. I have a pre-filter that is working brilliantly and means I hardly ever need to actually enter my canister filter. I also worked out how to install an in-line algae reactor. My system is now actually nitrate limited and so I am dosing to maintain them and phoshphates are in the ideal range.
 

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Check out my build thread that I just started where I talk about how I optimised my canister. I have a pre-filter that is working brilliantly and means I hardly ever need to actually enter my canister filter. I also worked out how to install an in-line algae reactor. My system is now actually nitrate limited and so I am dosing to maintain them and phoshphates are in the ideal range.
@chris_pull Please add specifics about your prefilter setup such as...
Brand/Model of the filter body
Specific item of LEDs you use

Some photos showing details of the prefilter and algae reactor construction would be awesome too. It looks like a very nice and clean setup, but it's hard to tell much about it without more photos and details.

Like you, long ago I ditched the filter foams in canister trays and loaded them with biomedia. But my canisters have the advantage of built-in/integrated yet easily removeable/serviceable foam prefilter assemblies. Your inline algae reactor wrapped with LEDs is a great idea. I'd like to build something similar for a much larger tank.
 
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@chris_pull Please add specifics about your prefilter setup such as...
Brand/Model of the filter body
Specific item of LEDs you use

Some photos showing details of the prefilter and algae reactor construction would be awesome too. It looks like a very nice and clean setup, but it's hard to tell much about it without more photos and details.

Like you, long ago I ditched the filter foams in canister trays and loaded them with biomedia. But my canisters have the advantage of built-in/integrated yet easily removeable/serviceable foam prefilter assemblies. Your inline algae reactor wrapped with LEDs is a great idea. I'd like to build something similar for a much larger tank.
Of course! I am going to pack it with as much information as I can and will go on a photo spree this weekend when I am doing maintenance.
 

Randy Holmes-Farley

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While I don't consider nitrate production and control to be a big deal these days, I'd point out a couple of reasons that the "nitrate" factory concept/concern does not necessarily disappear just by removing particulates.

1. The first is that we may not really want to speed up ammonia removal. Corals and algae prefer ammonia, and rushing to convert it into nitrate before corals get it may be counter productive.

2. One rationale for bioballs being a nitrate factory has to do with the media itself, not the detritus stuck to it. Here's a copy and paste from an article of mine detailing this issue:

Filters Designed To Facilitate The Nitrogen Cycle.

Filters such as trickle filters using traditional bioballs do a fine job of processing ammonia to nitrite to nitrate, but do nothing with the nitrate. It is often non-intuitive to many aquarists, but removing such a filter altogether may actually help reduce nitrate. Consequently, slowly removing them and allowing more of the nitrogen processing to take place on and in the live rock and sand can be beneficial.

It is not that any less nitrate is produced when such a filter is removed, it is a question of what happens to the nitrate after it is produced. When nitrate is produced on the surface of impermeable media such as bioballs, it mixes into the entire water column, and then has to find its way, by diffusion, to the places where it may be reduced (inside of live rock and sand, for instance).

If it is produced on the surface of live rock or sand, then the local concentration of nitrate is higher there than in the first case above, and it is more likely to diffuse into the rock and sand to be reduced to N2.

In a reef aquarium with adequate live rock, there is little use for a trickle filter, so in general they can be safely removed.
 

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While I don't consider nitrate production and control to be a big deal these days, I'd point out a couple of reasons that the "nitrate" factory concept/concern does not necessarily disappear just by removing particulates.

1. The first is that we may not really want to speed up ammonia removal. Corals and algae prefer ammonia, and rushing to convert it into nitrate before corals get it may be counter productive.

2. One rationale for bioballs being a nitrate factory has to do with the media itself, not the detritus stuck to it. Here's a copy and paste from an article of mine detailing this issue:

Filters Designed To Facilitate The Nitrogen Cycle.

Filters such as trickle filters using traditional bioballs do a fine job of processing ammonia to nitrite to nitrate, but do nothing with the nitrate. It is often non-intuitive to many aquarists, but removing such a filter altogether may actually help reduce nitrate. Consequently, slowly removing them and allowing more of the nitrogen processing to take place on and in the live rock and sand can be beneficial.

It is not that any less nitrate is produced when such a filter is removed, it is a question of what happens to the nitrate after it is produced. When nitrate is produced on the surface of impermeable media such as bioballs, it mixes into the entire water column, and then has to find its way, by diffusion, to the places where it may be reduced (inside of live rock and sand, for instance).

If it is produced on the surface of live rock or sand, then the local concentration of nitrate is higher there than in the first case above, and it is more likely to diffuse into the rock and sand to be reduced to N2.

In a reef aquarium with adequate live rock, there is little use for a trickle filter, so in general they can be safely removed.
Would you then say that there is an ongoing "safe level" of ammonia and nitrite to target in the typical aquarium? Or is that level so far below our testing ability to be impractical to measure?
 

Randy Holmes-Farley

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Would you then say that there is an ongoing "safe level" of ammonia and nitrite to target in the typical aquarium? Or is that level so far below our testing ability to be impractical to measure?

Ignore nitrite. it is essentially nontoxic at levels attained in reef tanks.

If ammonia was 0.1 ppm or higher total ammonia, I'd do something about it.

Ammonia and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

Ammonia Concentration Guidelines
Because ammonia's toxic effects appear at levels significantly below those that are acutely lethal (0.09 to 3.35 ppm NH3-N or 1.3 to 50 ppm total NH4-N at pH 8.2), and because some organisms in a reef aquarium may be more sensitive than the few organisms that have been carefully studied, it is prudent to err on the side of caution when deciding what concentrations of ammonia to allow in a reef aquarium or related system.

My suggestion is to take some sort of corrective action if the total ammonia rises above 0.1 ppm. This suggestion is also made by Stephen Spotte in his authoritative text, Captive Seawater Fishes.6 Values in excess of 0.25 ppm total ammonia may require immediate treatment, preferably involving removal of all delicate (ammonia sensitive) organisms from the water containing the ammonia. Some of the possible actions to take are detailed in the following sections listed below.
 
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