Water Change After Cycle?

[HIP-oboe-85]

I posted a week or so ago as being new here, and am looking for advice about what to do after the cycle is complete.

I have been testing parameters every day and got through the large ammonia and nitrite spikes a few weeks ago. It's going on about week 5 now, and I ghost fed a small amount of brine shrimp a few days ago. Ammonia and nitrites had a small spike later that day, and both were at 0 the following day (I am at work and do not have specific numbers handy). This means the tank is cycled, correct?

So now I am reading that I should do a water change to rid the tank of nitrates (which ARE high) before adding fish -- but what percentage? Some say 100%, others less. Advice?

 

[Brandon3152134]

In a cycle you are building up bacteria to take care of ammonia and nitrite which are toxic to fish. If your tank is 5 weeks old and its able to eat up ammonia and nitrite then it is cycled. I would do a water change and add a fish.

 

[cshouston]

What is your nitrate level now? That will dictate the percentage you should shoot for.

 

[ScubaFish802]

I agree with both posts above, the levels of nitrates would tell you how large of a initial change, and your tank sounds like it is cycled.

 

[HIP-oboe-85]

I believe it tested this morning at 60ppm (like I said I don't have the numbers with me just now). I'm using APIs testing kit, but am also taking a sample to be tested at my LFS in a while just to be on the safe side.

 

[Brandon3152134]

Whoa 60 ppm will kill a fish for sure. API is super inaccurate imo. I would definitely do a water change of at least 40 % if they are actually that high.

 

[cshouston]

I believe it tested this morning at 60ppm (like I said I don't have the numbers with me just now). I'm using APIs testing kit, but am also taking a sample to be tested at my LFS in a while just to be on the safe side.

I’d recommend at least a 70% water change to bring nitrates down under 20ppm. If it were me, I’d just do a 90-100% change, then stay on top of 10% weekly changes.

 

[Brandon3152134]

I’d recommend at least a 70% water change to bring nitrates down under 20ppm. If it were me, I’d just do a 90-100% change, then stay on top of 10% weekly changes.

The higher percentage the better in this case

 

[HIP-oboe-85]

Thanks guys. My tank was improperly cycled and I went too fast last time, and it hit my wallet HARD -- so trying to do everything exactly right this time. Was just afraid such a large water change would hurt it somehow!

 

[brandon429]

one of the best benefits of being cycled is no degree of water changing, literally no degree can uncycle it.

stopping feeding your tank wouldnt uncycle it, bacteria feed via natural means long before us when hydrated


doing a 100% water change twice a day for a year would not uncycle it.

doing a 100% water change, waiting an hour to refill the system lol, still would not uncycle it.

these claims would seem outlandish were they not already action threads and videos posted in our cycling threads. post-cycle is this tough, cannot be undone unless you dose and measure and maintain antibiotics or boil the setup.

I would bet 100 virtual dollars lol that even doing a 100% water change, filling with distilled water for half a day, then changing it all back for saltwater would not uncycle it (bioslick osmolarity regulation) but that's a guess, nobody has tested that yet
in all online cycles ever posted I have never seen a single cycle get undone, I dont think its possible in a home environment.


You literally dont have to consider your filtration bacteria for the rest of the life of the tank, even if you removed all your sand out in one of the 100% water changes (which we do for 40 pages in the sand rinse thread)

Knowing how tough filter bacteria can certainly save your reef from future loss, you have intervention and management options in play that someone fearful of bacteria would not, and the hesitation from that causes loss for sure.

 

[HIP-oboe-85]

Just to clarify, there are no fish in my tank. Only live rock and sand, and a few critters that stowed away on the rock that are thriving. The tank just finished the initial cycle and I was just asking for clarification about water changes prior to adding fish!

Also, number from this morning's test: ammonia 0, nitrite 0, nitrate was 40ppm (not 60 as I had misremembered).

 

[brandon429]

agreed fully ready to go, off that description alone all the above factors still meet. Change any degree of water you like, if you changed none thats ok too. nitrate is merely algae fuel it cannot kill anything we keep in reefing.

we do the end water change to have less uglies.

 

[excell007]

Just to clarify, there are no fish in my tank. Only live rock and sand, and a few critters that stowed away on the rock that are thriving. The tank just finished the initial cycle and I was just asking for clarification about water changes prior to adding fish!

Also, number from this morning's test: ammonia 0, nitrite 0, nitrate was 40ppm (not 60 as I had misremembered).

50% WC will take you to around 20ppm. having said this, 60ppm nitrate on a fowlr will not kill a fish if acclimated properly. I have a fowlr that was neglected for 3 years and nitrate crept up to >300ppm and never killed a fish. of course now it is 10ppm because I am trying to convert it into a reef.

 

[HIP-oboe-85]

Thanks for your help everyone! I just left my LFS -- I went to have my water tested just to be sure, and the one employee on duty said she "didn't know how." You all can see why I turned to this forum for help!

 

[cshouston]

I think 40ppm is a safe bet. You can do some napkin math if you know how much ammonia you added to cycle. 1ppm of ammonia = 3.6ppm of nitrate as the end product. Any decaying organics on your rock could increase that endpoint, though.

Either way, you won’t harm the cycle by doing a large volume water change. The lower your nitrate is to start with once you start adding livestock, the better.

 

[HIP-oboe-85]

The funny thing is, I have several freshwater tanks and have never done any of this testing. I use a water conditioner, let it run for a month and add some fish, and have never had any issues. All stock is still happy and healthy. I'm learning a LOT from this venture into reefing.

 

[burningmime]

How big is your tank?

If you have a 2000 gallon tank, a 50% water change isn't quick or cheap. There are other methods to reduce nitrates besides big water changes. Get a fuge going; may need to add something like caheto-gro and a little phosphate to get it started. Get a skimmer going and dose some carbon (eg NO3O4-X or just vodka).

 

[leighla wolf]

Whoa 60 ppm will kill a fish for sure. API is super inaccurate imo. I would definitely do a water change of at least 40 % if they are actually that high.

I agree. 40% change, see how your ammonia, nitrite, and nitrates go and if you need you can always do another water change. It’s easier take less and than to go overboard and that way you can ensure you don’t break your cycle. Most of your bb is on your surfaces and media not the water column.

 

[HIP-oboe-85]

It's just a 30 gallon. I bought a skimmer today to go with all the other equipment I'm accumulating...

 

[HIP-oboe-85]

How big is your tank?

If you have a 2000 gallon tank, a 50% water change isn't quick or cheap. There are other methods to reduce nitrates besides big water changes. Get a fuge going; may need to add something like caheto-gro and a little phosphate to get it started. Get a skimmer going and dose some carbon (eg NO3O4-X or just vodka).