55 Gallon Tank Do I Still Need To Do Pwcs If There Are No Issues With Ammonia/nitrites/nitrates?

When do you do a partial water change?

  • When the tank starts to look dirty

    Votes: 0 0.0%
  • Strict schedule (every 3 days, once a week, etc.)

    Votes: 9 100.0%
  • When ammonia levels are greater than 0.

    Votes: 0 0.0%

  • Total voters
Hi, I only started keeping fish in early Sept., but I've spent hundreds of hours spent reading fish forums, books, etc.

Two weeks ago, I moved my fish from a 10 gallon to a cycled 55g, and have been adding additional small fish every few days. The 55 gallon is now 80% stocked (based on adult sizes) and 150% filtered. My little fish are all low-polluting, and I have 8 live plants and 7 large moss balls.

I've been doing a complete API liquid-chems water test every day, and levels are always: 0 ammonia, 0 nitrites and ~2 nitrates.

People on these forums are always recommending tons of partial water changes (PWCs): anything from 30% every few days, to 10-50% weekly. But I've assumed this was to control rising ammonia levels. If my ammonia is perpetually 0, is there any reason to do a PWC? After all, an unnecessary PWC can be stressful/disruptive to fish, and cause decor to move, potentially crushing/killing an innocent cory (don't ask me how I know this). So I'd like to do as few as possible, while still keeping my water quality optimal.

How do you decide when to do a PWC? Do you do them on a strict schedule, regardless of ammonia levels? Or do you only need to do them when ammonia is >0?
I would reccomend a combo, always do them weekly regardless of parameters, I do 50% weekly (which is bigger than normal bit that's just me). But if your parameters are high, do another. If the test results a tiny bit high, do a smaller one, if there pretty high a bigger one. Hope this helps!
One of the other reasons for doing partial water changes is to replenish the tank water with minerals - they are important for the health of fish & inverts.
Water changes or the lack of them is a long running point of contention with fish keepers.

I only do them when the readings call for them. BUT I must stress this>I use remineralized RO/DI water from my system. I top off with straight RO/DI. If a person is on city or straight well water you want to do weekly water changes. The reason is heavy metals and other things can over time build up if you simply top off for evaporation.
Every 3 days might be a "ton". But weekly is just standard and necessary in my opinion. Weekly does not equate to "tons of water changes". You do this to control nitrates more than anything.
I try never to go no more then 2 weeks without doing a water change,at the very least like 30% to 40% a week or 50% every other week if my stats are ok, IMO I think there can be such a thing as to many water changes,like doing 50 every other day would be unnecessary,unless your having very high readings and there's a need for you to do it .After a water change it takes some time for things to settle down again, and I think to much of this can also stress the fish.Not enough either can be just as bad, try to get the right balance. And I also agree with the above poster that when you do water changes you replenish the tank with minerals
With my recent change in ferts I now do weekly %50ish water changes as well on my 5, 9, and 10 gallons. My 30 gallon I do minimum %25 to %50 water changes at least every 1.5 weeks. My 1.5 hasn't been changed in about a month or more because I'm making sure it's cycled to add shrimp. The ferts I use go by EI dosing so changing more of the water in my case is essential for the water quality, as well as to replace minerals and such in my other tanks for the shrimp and snails. That and being that most of my tanks have shrimp and snails, I like making sure the gravel stays clean because it just looks good. This all goes with saying my 5, 9, and 10 are almost always cleaner or cleaner looking then the 30.
First off a cycled tank should never show ammonia since in a cycled tank the nitrogen cycle will convert them to nitrires then to nitrates. Most people recommend weekly water changes since there is so much more to water chemistry then what we typically test for. Now in a planted understocked tank it is possible to do them every other week to keep nutrients a little higher for the plants but its a balancing act. Now honestly I don't think you can actually do too many water changes as long as you have good source water. The key is to be consistant since the beneficial bacteria will grow to what ever amount is needed to convert the waiste. So if your doing by weekly water changes and just slack off for a month the bacteria will be over whelmed and it will end up hurting your fish till they could catch up.
I test my tank every Monday and regardless of what the test shows which is usually good I Still do a min of a 30% water change to keep HAPPY FISH and the tank the best I can keep it.

Thanks Bill
  • Thread Starter
Thanks for your input, everybody! I think the mineral build-up must be the main reason, but I want my tank to keep looking great and fish to stay happy, so I'm on-board to continue the weekly changes I've been doing all along. I wanted to see if I could slack a bit, but the answer is resounding no!

Random Great Thread

Know of a great thread on Fishlore that should be on this list? Submit the thread link here:
Great threads on Fishlore

Latest threads

Top Bottom