Need Filtration and Substrate Advice 75 Gallon Planted Tank

1- I am going back and forth between HOB, Submersed, or Cannister filter. Can somebody explain to me why whether it is worth it or not to invest in a canister filter over a Fluval C Power Series (HOB)? I understand that canister filters can be customizable but could they cause too much hassle and too much suction to be worth it in a planted tank?

2- Also, I have seen so many conflicting opinions over sand, soil, sand/soil, etc for my substrate that I have absolutely no idea what the best decision will be. Soil has the nutrients but others say sand will work fine with fertilizer supplementation.

3- Finally, CO2 injection. If I am diligent about lighting appropriately, do I REALLY need this? Could this be a bad thing if I reach a moderate stocking of fish in a heavily planted tank? I have met a few locals that advise me not to bother with CO2....


I am definitely wanting to invest in whatever will give me the best results for my 75-gallon setup and will take whatever advice I can get.
Thanks all

What are the tank dimensions (length x width x height)?
What sort of fish do you want to keep?
Do you want a planted tank?
What lights are on the tank?

Colin_T said:

What are the tank dimensions (length x width x height)?
What sort of fish do you want to keep?
Do you want a planted tank?
What lights are on the tank?

Click to expand...

Hey Colin,

48x18x21
I want to keep tetras (if successful, I will slowly add a LOT of them) with my 3 Mollies.
Yes, I want to plant heavily

The lights I have are:

hygger Advanced Multi-Color Full Spectrum LED Aquarium Light with 24/7 Lighting Cycle Custom Color Intensity Mini Fish Tank Light with Timer for 12-54 in Freshwater Planted Tank
https://www.amazon.com/gp/product/B08N4CBTJP/?tag=ff0d01-20​

I will probably go with blue tetras or neon tetras. I think my mollies will stand out nicely among them.

Something'sALittleFishy said:

1- I am going back and forth between HOB, Submersed, or Cannister filter. Can somebody explain to me why whether it is worth it or not to invest in a canister filter over a Fluval C Power Series (HOB)? I understand that canister filters can be customizable but could they cause too much hassle and too much suction to be worth it in a planted tank?

Click to expand...

Your last question is indeed the issue...in a planted tank, filtration only has one real function, and that is mechanical (the clear water aspect) that provides adequate (this depends upon the fishes' requirements) flow. The filter return should create sufficient surface disturbance to provide a good exchange of oxygen/CO2, but at the same time you do not want so strong a current down the tank that the plants sway (except those closest to the filter return obviously). I had Eheim Pro II canisters on my 70g, 90g and 115g tanks, and I was able to provide sufficient but not excessive flow. Even so, it was interesting how many of the forest fish (tetras, etc) tended to remain at the "quiet" end and not at the end where the filter return was positioned. I personally do not like HOB, I had two or three many years ago that ran dry and burnt out (during a very brief power outage when I was, of course, away from home). But I have never kept fish that need a waterfall so this sort of filter has no appeal to me, but others like them.

Something'sALittleFishy said:

2- Also, I have seen so many conflicting opinions over sand, soil, sand/soil, etc for my substrate that I have absolutely no idea what the best decision will be. Soil has the nutrients but others say sand will work fine with fertilizer supplementation.

Click to expand...

First, aquatic plants will grow in any substrate provided the grains are not too large, which means, pea gravel or larger. Sand is the ideal substrate, and it also suits most if not all fish (some, like cories, need soft sand). Soil has more trouble than benefit; after one year it has no nutrient value beyond what an inert sand substrate has, and the only nutrient value during the initial year is the release of CO2 and ammonia from the organic decomposition, and with fish in the tank you don't need more of this. The so-called plant substrates are usually a total waste of money. It is the light, balanced by nutrients, that determines plant response. Floating plants and those attached to wood or rock gain no benefit from the substrate anyway. And it is easy enough to insert a Flourish Tab next to each of the larger substrate-rooted plants (swords really benefit) once every 3-4 months.

Something'sALittleFishy said:

3- Finally, CO2 injection. If I am diligent about lighting appropriately, do I REALLY need this? Could this be a bad thing if I reach a moderate stocking of fish in a heavily planted tank? I have met a few locals that advise me not to bother with CO2....

Click to expand...

Diffused CO2 is another "more trouble than benefit." It does impact fish, this is becoming known. The organics from the fish that settle into the sand substrate provide more CO2 than many realize, and of course there is also the normal respiration of fish, plants and some species of bacteria. If you are planning a high-tech aquatic garden where the plants are the focus and fish are, well, absent (for their own health!) then diffused CO2, daily fertilizers, and mega light can be useful. But not in a low-tech method or natural planted tank where fish are the emphasis.

The lighting unit linked should be good. You need to balance it with complete nutrient supplementation, and then use the duration to avoid algae issues. Floating plants also help, and are appreciated by the forest fish you are considering anyway.

Photos below show what is possible with the method outlined above. Two versions of the 70g, one in 2009 and the other in 2016.

Byron said:

Your last question is indeed the issue...in a planted tank, filtration only has one real function, and that is mechanical (the clear water aspect) that provides adequate (this depends upon the fishes' requirements) flow. The filter return should create sufficient surface disturbance to provide a good exchange of oxygen/CO2, but at the same time you do not want so strong a current down the tank that the plants sway (except those closest to the filter return obviously). I had Eheim Pro II canisters on my 70g, 90g and 115g tanks, and I was able to provide sufficient but not excessive flow. Even so, it was interesting how many of the forest fish (tetras, etc) tended to remain at the "quiet" end and not at the end where the filter return was positioned. I personally do not like HOB, I had two or three many years ago that ran dry and burnt out (during a very brief power outage when I was, of course, away from home). But I have never kept fish that need a waterfall so this sort of filter has no appeal to me, but others like them.



First, aquatic plants will grow in any substrate provided the grains are not too large, which means, pea gravel or larger. Sand is the ideal substrate, and it also suits most if not all fish (some, like cories, need soft sand). Soil has more trouble than benefit; after one year it has no nutrient value beyond what an inert sand substrate has, and the only nutrient value during the initial year is the release of CO2 and ammonia from the organic decomposition, and with fish in the tank you don't need more of this. The so-called plant substrates are usually a total waste of money. It is the light, balanced by nutrients, that determines plant response. Floating plants and those attached to wood or rock gain no benefit from the substrate anyway. And it is easy enough to insert a Flourish Tab next to each of the larger substrate-rooted plants (swords really benefit) once every 3-4 months.



Diffused CO2 is another "more trouble than benefit." It does impact fish, this is becoming known. The organics from the fish that settle into the sand substrate provide more CO2 than many realize, and of course there is also the normal respiration of fish, plants and some species of bacteria. If you are planning a high-tech aquatic garden where the plants are the focus and fish are, well, absent (for their own health!) then diffused CO2, daily fertilizers, and mega light can be useful. But not in a low-tech method or natural planted tank where fish are the emphasis.

The lighting unit linked should be good. You need to balance it with complete nutrient supplementation, and then use the duration to avoid algae issues. Floating plants also help, and are appreciated by the forest fish you are considering anyway.

Photos below show what is possible with the method outlined above. Two versions of the 70g, one in 2009 and the other in 2016.

Click to expand...

This was an incredible response! Thank you for taking the time to explain this to me and in such good detail. I ended up with a Penn Plax Cascade 1500 canister filter for my filter. I am thinking about doing a 1:1:1 blend of fine gravel, medium-grain sand, and aquasoil because of the short-term nutrient benefit and because I liked the consistency and appearance of the blend.

My next question will be how will I know how to position the canister filter's input and output lines and how do I make sure that I am not blowing plants away by the current from the output line?

Something'sALittleFishy said:

This was an incredible response! Thank you for taking the time to explain this to me and in such good detail. I ended up with a Penn Plax Cascade 1500 canister filter for my filter. I am thinking about doing a 1:1:1 blend of fine gravel, medium-grain sand, and aquasoil because of the short-term nutrient benefit and because I liked the consistency and appearance of the blend.

My next question will be how will I know how to position the canister filter's input and output lines and how do I make sure that I am not blowing plants away by the current from the output line?

Click to expand...

You're welcome.

On the substrate blend...you should not keep cories or similar substrate-level fish (including cichlids) with this intended substrate. Just so you know. And again, there is really no nutrient benefit.

When you can (by using the hoses of the filter, if it has these) the intake and return should be at opposite ends lengthwise. This ensures a flow down the tank from either left to right or right to left--which may matter, as fish do tend to swim "upstream" and in an aquarium with a flow down the tank they will tend to be in this direction more often that not. The return should be at the surface so some disturbance can occur. The filter intake should be close to the substrate at the opposite end, but not so close that the substrate is disturbed which means likely getting sucked up. Usually 5-6 inches above the substrate works.

The return can be aimed into that end wall to lessen the flow as it travels down the wall and across the tank, or if it has a spraybar that can be placed along the end wall with the holes adjusted to produce surface disturbance but less direct current. Another trick to lessen the flow is to aim the return into the end wall and have a large chunk of wood or rock just out from the wall, so the flow is further dispersed. A good plants for this is Java Fern attached to the wood/rock, as this plant tolerates strong flow better than many. I have had sword plants slowly wither to nothing simply because they were in this corner and subject to strong currents.

Byron said:

You're welcome.

On the substrate blend...you should not keep cories or similar substrate-level fish (including cichlids) with this intended substrate. Just so you know. And again, there is really no nutrient benefit.

When you can (by using the hoses of the filter, if it has these) the intake and return should be at opposite ends lengthwise. This ensures a flow down the tank from either left to right or right to left--which may matter, as fish do tend to swim "upstream" and in an aquarium with a flow down the tank they will tend to be in this direction more often that not. The return should be at the surface so some disturbance can occur. The filter intake should be close to the substrate at the opposite end, but not so close that the substrate is disturbed which means likely getting sucked up. Usually 5-6 inches above the substrate works.

The return can be aimed into that end wall to lessen the flow as it travels down the wall and across the tank, or if it has a spraybar that can be placed along the end wall with the holes adjusted to produce surface disturbance but less direct current. Another trick to lessen the flow is to aim the return into the end wall and have a large chunk of wood or rock just out from the wall, so the flow is further dispersed. A good plants for this is Java Fern attached to the wood/rock, as this plant tolerates strong flow better than many. I have had sword plants slowly wither to nothing simply because they were in this corner and subject to strong currents.

Click to expand...

I have been told that a local fish store specializing in showroom setups has some kind of device that dilutes/spreads the direction of current from the output line in several directions so it is not too forceful in any one direction. Have you heard of anything like this or is this a waste? Would it be intelligent to reduce filtration (reducing output) then buy one of those attachments that generates a current? I don't remember what those are called but I can see their benefit

Hello
It is advisable to have a pump whose flow rate is at least 5 times tank volume.

Avel1896 said:

Hello
It is advisable to have a pump whose flow rate is at least 5 times tank volume.

Click to expand...

I have read stuff like this before. The Penn Plax Cascade 1500 does 350 gph and 75*5 is 375. I think that's probably close enough. Heck, I will add a sponge filter somewhere if need be

Sponge filter filters only particules (mechanically).
Biological filter (and substrate) houses "good bacteria". Mine is Aquario Neo Media Pure and I would't change it for anything else.

Something'sALittleFishy said:

I have been told that a local fish store specializing in showroom setups has some kind of device that dilutes/spreads the direction of current from the output line in several directions so it is not too forceful in any one direction. Have you heard of anything like this or is this a waste? Would it be intelligent to reduce filtration (reducing output) then buy one of those attachments that generates a current? I don't remember what those are called but I can see their benefit

Click to expand...

Seems to function something like the spraybar. I found that over time, on my larger tanks (70g, 90g, 115g) with canister filters, I preferred the filter return without the spray bar; not sure why I went with this, but I did...maybe because the spray bar holes kept getting algae growing, but I think more because I wanted a good surface disturbance.

From the last few posts on return rate, biological filtration...

Remember we are dealing with a planted tank here, so biological filtration is not needed (beyond what will occur naturally with or without any filter) and should not be "encouraged" by fancy filter media that only costs a fortune. And flow should be what the intended fish require, and nothing more; this will be sufficient to provide surface disturbance and mechanical filtration through the sponge/foam media. The great benefit of a planted tank with forest fish is that we are spared a lot of extra work and expense.

I come at this from a slightly different perspective to Byron here but completely respect his knowledge and advice, and if followed you will have a successful tank but just wanted to add my 2 cents

I have a high tech tank that has been set up for just under a year now, I have tropica aquarium soil which is a nutrient rich substrate - like most of the others it is not actually soil but pellets of crushed lava rock that contains some of the elements you get in the root tablets of the same brand, but in a much lower quantity. So in my mind sand + root tabs works equally well as aquarium soil but for me aquarium soil has 2 benefits over just sand. If you want to create an aquascape like you see on You Tube you want to create height at the back of the tank which can mean stacking substrate to a point where if it was sand you would encounter problems with anaerobic bacteria build ups. Secondly the sand and root tab options work great for things like Amazon Swords, Crypts, Valis and some stem plants but if you want to produce a carpet in your tank Aquarium Soil is better because the mesh of plants that a carpet requires will be getting fed more equally.

I also inject a very low quanity of Co2. This has been higher at the 30ppm level a lot of planted people recommend which from my regulator was meaning about 5 bubbles per second where as now I am at not even 1 bubble per second and still getting good results, I use a drop checker with a ph solution and it never changes colour now, showing how little is going in, but from experimentation I know it makes a difference. Without Co2 the plants go pale and dont grow as fast. Having the Co2 means you can grow a wider variety of plants (things like Rotala, Juncus, Fissidens, Hair Grass, carpeting plants) and faster, which in aquascaping terms can be important if you aspire to enter contests as you will want to mature the scape in around 6 months. The downside is that you should only moderately stock a Co2 tank - I'll never add as many fish to this tank as I would if I didnt have Co2 for example.

Flow for me is important too as I use the filter outlet to disperse the Co2 bubbles around the tank, I have 900lph going through a 100 ltr tank which gives me 9x turn over. I'm now choosing fish like Stiphodon Gobies that do well in that flow. Equally as I use the flow to help with the Co2 distribution I have a powerful light unit to make sure my plants have the right combination of elements for fast photosythesis.

I do all of the above because thats what I enjoy, I really love maintaining the plants, the trimming process etc, I bought a nice set of tools to work with and in combination with having the radio on I really love getting to work on the tank each week, thats my "me" time. This works for me because I didnt set this tank up with the focus being on fish, I'm not going to come home every week from the LFS with a bag of new fish (been there done that). My tank is purely for me to enjoy a slice of nature and the artistic side that aquascaping gives the opportunity for. And I choose to do that slowly.

I guess what I'm trying to say is if you want to dive in and explore loads of cool fish and combinations of them, hunting out some rarities and learning from that side the Co2 high tech route isnt for you. If you want to take a path closer to what I've described above maybe it is?

Wills