Why does my tank smell?

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If the parameters are ok and you are concerned about the smell add some activated carbon.
 
Haha no worries, it took me a good bit of reading to understand it better and decide how I wanted to customize my filtration.

Don't fret: the filtration you have is fine, I'll try to explain a little more depth and it can actually save you $ in the long run. Afterward, I'll edit the post with a couple articles if you're interested.

So your filtration goes in stages. Not sure you have a mechanical stage though.

1st stage: mechanical - typically a intake sponge or a sponge after your impeller (or both) and before your other filters. Used to pull out and catch larger debris (just rinse off in dirty tank water every now and again) and other large particulate matter. I use both for a 2 stage mechanical filtration.

2nd stage: chemical - typically the pads (in your case the blue pads with carbon in them). Used to catch dissolved pollutants. I use a dual-sided filter floss (polyfill basically) for a 2 stage chemical.

3rd stage: biological. Houses 1 source of your bacteria (also sources present in the substrate and some in water, but we use the filter bio media as a "homestead" for the bacteria). The key to the bio media is: the more surface area the better (more room for your beneficial bacteria). I use the ceramic bio cubes (look like small cylinders) and place them all facing the same direction (point so water goes through the hole) and cram as many as you can fit. *Edit - a lot of filters come with a type of plastic screen/sheet to work as biological filtration, feel free to scrap that and replace with something better (replace smartly though).

By customizing these you can increase the effectiveness of your filter. In your case - you use the blue pads with carbon in them. Which is fine - but activated carbon has a lifespan, and once spent when you change out the pad with carbon in it - you can affect your cycle. Always best to reuse filters for a long time, just can't do that really with filters that have carbon inside them. Activated carbon will pull out some chemicals, tannins, and some nutrients that your plants use (generally not enough to affect plant growth), so it does help to clean water - just doesn't last forever.

To save money, and help your beneficial bacteria - you can buy a large sheet of dual sided polyfill (will work as a 2 stage chemical filter) and cut out the sizes of filter you need (link below to an example of this). The sheet will last forever. Then you could switch to a small media bag and fill it with Purigen (I suggest) or activated carbon and place it before the poly. This way, you can change out the carbon/Purigen without changing the chemical filter (which also houses beneficial bacteria). During times you do need to change the chem filter, simply place a new on in the filter a few days before pulling out the old one.

Purigen also lasts a long time - and it can be cleaned/"recharged" for further use. I just bought the bag that treats 100 gallons, split it in 2, and put in media bags. Before taking 1 out for "recharging" I put the 2nd one in a few days beforehand (same as the filter floss).

I'm not the best at explaining stuff and will link some articles. Hope this helped to explain how filtration works a bit more - there are options within each stage to customize it to suit your needs.

*Edit:

HOB customization video - full of info.


*Edit: HOB customization guide (uses a topfin silentstream filter and explains various ways to customize, but all hob filters can be similarly customize, I have 3 customs filters: a topfin silentstream, a Fluval Aquaclear, and an aqueon slow-flo for shrimp - all 3 are designed different but all have same custom filtration).


*2nd edit: explanation of filtration stages


Product links for a few things:



Purigen works in these media bags but the link for the Purigen I tried is broke. Its like $13.00 for a bag that treats 100 gallons (split between your own media bags). My custom filtration helped my water clarity a lot, but it's really the Purigen I credit for pulling out the smell.
Thanks for this thoughtful response. I need to read through it in detail when I have time. Here are a couple of pics of my current filter setup (sorry, they load sideways). It looks like both essentially have two filter slots which I presume is for this type of custom filtration? The back slot for the first stage and the forward slot (closest to tank) would be second stage?

I will be happy if I can avoid having to buy these pre packages blue filters. And if it’s cheaper and better to go away from that I’m all for it.
 

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Thanks for this thoughtful response. I need to read through it in detail when I have time. Here are a couple of pics of my current filter setup (sorry, they load sideways). It looks like both essentially have two filter slots which I presume is for this type of custom filtration? The back slot for the first stage and the forward slot (closest to tank) would be second stage?

I will be happy if I can avoid having to buy these pre packages blue filters. And if it’s cheaper and better to go away from that I’m all for it.

Np! The video and DIY article right below my last post will prob. be the most informative.

But, I still think the Purigen or regularly changed activated carbon will help a lot. Customizing just lets ya change these without changing your chemical filtration and interrupting the cycle. Ideally you want all 3 stages they discuss in the video and article, I put Purigen/carbon before the chemical stage after the mechanical stage.

If you customize though, don't do it all at once so as to not disturb your cycle. Normally customizing a filter happens at the start of a tank with a new cycle.

To accomodate that, try to switch x1 piece of any new type of filtration at a time into it with the old filtration for a week or 2 before pulling out the old stuff - don't wanna kill your cycle swapping everything out at once. Slooowly swap things over x1 filtration piece at a time (you prob. won't have space to do more than 1 new piece at a time).

I'd start with a new chem. filter since they squish in easily, when you pull the old one out a week or 2 later just straighten this one out (cut to size before initially squishing in). Once you pull out the old one, add your media bag of purigen or activated carbon before the new chem. filter (pulling out the old cartridge w/ frame will free up more space for the media bag to fit).

Definitely read up on Purigen too! It's awesome stuff - just like good quality activated carbon but better, lasts for months and can be recharged instead of buying more carbon (poor quality activated carbon doesn't last long at all..I also use a different "recharge" method).
 
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I just got a bunch of stuff originally for canister filters and cut it down to the size of my hob filter. I also have a carbon cartridge, but I've left it running so long the carbon isn't doing anything, just providing some space for nitrifying bacteria.
 
so true, you should only clean your filter once a month in aquiarium water from a water change, if you just toss it in to the trash you get rid of lots and lots of beneficial bacteria.
Actually, it should be cleaned every 2 weeks according to @Colin_T.
 
I had a tank smell for a few days after adding java fern. Added any plants?
 
I probably need to add plants. I’ve never had plants before.

I’m starting to get some unwanted green algae. I’m also wondering if this has anything to do with the smell. Is this type of green algae fairly normal in a new aquarium setup? I’ve been trying to keep the light exposure to a minimum (4-6 hours per day). Here’s a pic. You can see there is a fair bit starting to bloom on the pot. It’s also on other items (seashells and caves). I have a small common pleco but it isn’t touching this stuff.
 

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I probably need to add plants. I’ve never had plants before.

I’m starting to get some unwanted green algae. I’m also wondering if this has anything to do with the smell. Is this type of green algae fairly normal in a new aquarium setup? I’ve been trying to keep the light exposure to a minimum (4-6 hours per day). Here’s a pic. You can see there is a fair bit starting to bloom on the pot. It’s also on other items (seashells and caves). I have a small common pleco but it isn’t touching this stuff.

Yeah green hair algae is pretty common during cycling. Most all healthy aquariums will have some algae present, but when it starts growing like that you can reduce your lighting, if you have no live plants or fish and it's just cycling a blackout treatment will kill it off. With fish, reduce down to 9-10 hrs of light at a time (plants don't need as much as green hair algae tends to thrive with). Sometime, using too little light will also promote algae growth - so kinda gotta work a balance over time. There is a few light reducing methods / schedules you can find info. for, they all will generally help.

Live plants will also help with that a lot, as enough of them (some do better jobs with certain things than others) will soak up ammonia/nitrates etc. Etc., Helping to starve the algae. Fast growing plants like pennywort, moneywort, frogbit and similar will usually outcompete algae for nutrients.

Be wary of what plants you buy, and get used to scientific names =P it will help a lot when looking around. Different plants will need differing lights levels, fertilizers, etc. (Some even need co2 systems to thrive, can be pricey) so make sure to get plants that work with what you can provide them. If you find your lights are too bright you can use floating plants or even tannins to reduce light lvl. *Note that Purigen and activated carbon will remove tannins - so you can't reduce light with them if you use these to reduce smell.

Don't let it overwhelm ya though, if you stick to 'easy' care level / hardy plants you'll be fine it's easier than it all sounds. If you get plants that root into the ground and rely on substrate for nutrients, get Root Tabs. If you get plants that rely on the water column for nutrients, use a liquid fertilizer (flourish is the usual recommendation). Starting out - avoid plants that need co2.
 
Actually, it should be cleaned every 2 weeks according to @Colin_T.
Filters should be cleaned at least once a month and every 2 weeks is better. However, do not clean a new filter until it has been fully cycled and then wait 2 more weeks before cleaning it for the first time.
 

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