Discus Advice on Filtration and WC's


Hi everyone! I've currently been obsessing with keeping discus for over the past two years now and really want to make it my goal this year to properly house these fish in my aquarium.

Currently, I have a 70 gallon aquarium in my families dining area that only houses my seven remaining angelfish that I had raised a few years back. The tank is two or three years old at this point and has a HOB filter specifically designed for 70 gallon aquariums.

And just to pour down everything that I've learned so far about these specific fish (the Discus): they're a fish that prefer mid/high 80 temperatures such as 85 to 88, need a minimum of at least a 70 gallon (or 75 based on other sources), need a varied diet so that they don't become dependent on one food only, at least 1 discus per 10 gallons if you're beginning, and that there should be consistent water changes in order to properly house these fish since they don't tolerate ammonia, nitrites, and nitrates all that well.

Now that that's out of the way, my aquarium temperature is roughly 84-86 at the moment (since I believed that I was going to house Discus last year, but had horrible luck with cansiter filters) and I've obtained a variety of fish food such as pellets, flakes, freeze dried, frozen, and perhaps live in the future such as black worms and white worms if I believe that aren't harboring any parasites.

However, I'm currently stuck on what type of canister filter that I should buy for my 70 gallon aquarium and also how to properly do water changes for these fish.

Last year, I ordered a polar aurora cansiter filter which lasted a month, returned it, got another polar aurora which only lasted for two weeks, and never got a response from the dealer for a whole month. So that was quite a bummer. Then after that, I ordered a Marineland canister filter and the filter began immediately leaking once I turned it on (luckily I was outside for this), returned it, got another one, and had the same problem. Tried all of the obvious ways to try and fix the problem, but nothing seemed to work.

And because of my entire fiasco with these canister filters, I looked into making my own internal filters for my aquariums by cutting up a bucket in half, placing it in a corner of the tank, and using a sponge pad to house all of my biological and mechanical filtration. But now I'm worried that that wont be ENOUGH filtration for the Discus, ultimately resulting in a loss of these fish!

So that's the first part (what type of filter to use), the second part is what is the best way to change the aquarium water?

For the past two years now, I've always added in my Prime dechlorinator first, and then pumped in my tap water either straight from the sink or from the hose outside. Never had any problems with any of my fish. And based a few answers that I got a long time ago, I was told that this was a very risk way of changing my water if I wanted to keep Discus since they may accidentally intake the prime or tap water and get sick because of it or from the sudden temperature swing. So I was told that it was recommended to have aged water in a large tote next to the aquarium (roughly 2-3 days old before use) with a heater in it so that the temps are the same to use for my water changes instead. Could I still do water changes even though I put prime in before the chlorinated, not the same temperature water? Or would my chances of success be better if I used a large tote of dechlorinated, same temp water next to the aquarium? Asking this question since I was also told that some fluctuation in temperatures can actually help the Discus become more tolerable of sudden changes, resulting in them being hardier in the long run.

But those are my main concerns at this very moment! I would like to hear other experienced fish keepers feedback on what type of canister filter to use (or perhaps a sump!) and also some advice on how to do water changes. Thank you all in advance!

EDIT: I should also mention that I'm not trying to reach the best of the best here! But just as a regular fish keeper and not for show!


Everyone has their own preferences regarding canister filters. I like Fluval and Eheim Classic canisters. For 70 gal I would go with 1 x Fluval FX4 or 2 x Fluval 407 or 2 x Eheim 2217 or one of each. Discus like quiet water so the Eheims would be good with their somewhat lesser flow and spray bar attachments though any of them can be modified or managed in various ways to minimise current. A sump is certainly an alternative.

I personally think that it’s important for water change water to be similar to the temperature of the tank water so as not to shock the fish. I add Prime to the tank (accounting for the entire tank volume) and then add tap water of at least close to the same temperature. I have not had any issues but as you mention, there is some risk to this approach. It is preferable, especially with sensitive fish, to add dechlorinated water to the tank.

I should mention that I am not a Discus keeper! Hopefully some members who are will chime in.


I have a pen plax cascade 1500 on my 75 gallon discus tank. Also a sun sun UV filter and a marinland polishing filter. No problems ever - knock on wood! I also have a Hydor 350 on my 45 gallon cichlid tank with no problems.


Welcome to the Community!
Bravo, your doing research and asking the right questions.
I started with Discus just about 1 year ago and participate in a "Great" thread with other relative "Newbie" Discus keepers. We have been sharing our "Trials and Tribulations" a ton of info. I highly recommend checking it out:


Also, here is my thread I started with more info from my start-up to present:

Jmaldo's Discus Build | Freshwater Aquarium Builds 402889

Between the two, should answer most of your questions.

Good Luck!

Learning all the Time.

86 ssinit

Lots of good info above!! With discus filtration isn’t really an issue. You will be doing so many water changes that some just use sponges on bare bottom tanks without a problem. But as you said your just looking to enjoy the fish no show fish. I’m with you . My tank is planted . my tank is a 125 and I use an fx6 and an odyssea 350 to filter. I change 50% water every 2 days by vacuuming the gravel. Got to keep the water clean. The more like a regular fish tank the more work . For your tank you could use a pair of marineland 350 hob filter or an fx4. The fx canisters are a little easier to work with than regular canisters. I put a sponge over the intake and rinse it at every wc.

Now for me the angels have to go. Sorry fern few have luck with angels and discus and those that do usually add them together at the same size. So they grow together. Your being in that tank will be dominant and stress the discus. Even by putting them in at the same age it still might not work. I like both but keep in different tanks.

As to water changing that’s going to be up to your water source. And from what your saying your source seems good. What I do is filter my water from the tap through an under counter type filter. This removes chlorine and some other bad stuff before it goes into the tank. No need for prime now. I’ve never used prime. May cost $100 to build but will last a life time. Mine is over 25yrs old. Ask if you would like pics. Next the incomeing water needs to be the same temp as the tank water. Clean water is a must!! You’ll start doing 50% water changes daily for at least a month. Your fish should grow an inch or more. Than you can go to every other day for probably the next 4-6 months. When they get to 6months you can reduce your water changing to what works best for your fish. After doing all these water changes you will know how your fish are.

Lastly buy your fish online. Ask us who we recommend. But from just one seller don’t mix. And as jmaldo says stop buy and say hello at the discus gang updates thread. Great group that are all willing to help .

Similar Aquarium Threads

  • Question
  • Poll
86 ssinit

Random Great Thread!

New Discus Threads

Latest Aquarium Threads

Top Bottom