Combating high nitrates, should I do a 100% water change or only 50%?

[Alpha_and_Gec]

As the title states, I am trying to clear out a very significant amount of nitrates(>80ppm as of this morning) via a large scale water change and would like my fish and corals to remain alive throughout the procedure(needless to say I’ve never done a water change at this scale before). I’ve taken care to ensure the replacement water is as close to identical to the tank water in terms of pH as possible. In this situation, should I go through with the procedure and replace all the tank’s water, or will changing only 50% of the water be sufficient to remove most of the nitrates? I’m mainly just worried about my animals dying of shock and potential air exposure.

My stock:
1 Dascyllus melanurus(I actually have no clue how he’s survived all these years in here)
2 hermit crabs of some sort, one with blue legs and another with red. They have similar limb proportions and I was never able to get a good look at them(or cared enough) to get a positive ID. They’ve been around since the beginning and I suspect they’re immortal.
3 - 4 various Cladiella spp. leather corals.
1 head of a very sad, very unhealthy branching hammer coral that keeps getting covered in filamentous every few weeks.
1 red or orange - coloured mushroom coral lodged in a hole that I can’t get a good look at.
2 bubble anemones that split from a single one like one and a half years ago.
2 rock flower anemones.

 

[SPR1968]

You don’t say what size tank it is, but I would spread it over a few days if it’s easy enough, then you shouldn’t have any issues.

Smaller changes spread over a period are better, unless of course there’s good reason like an emergency etc.

 

[Macdaddynick1]

Check your test kit and do 50%. You definitely don’t want to go from 80 to 0 nitrates. Ever. Nor do you want to go below 20 anyways . Just my .02

 

[Alpha_and_Gec]

You don’t say what size tank it is, but I would spread it over a few days if it’s easy enough, then you shouldn’t have any issues.

Smaller changes spread over a period are better, unless of course there’s good reason like an emergency etc.

Oh right, forgot the most basic info lol
80 gal display tank, filter setup is mostly biological with a skimmer and a colony of caulerpa algae covered in filamentous algae. I used to change very small amounts very often to compensate for the lack of a large container, but that never worked to deal with this level of nitrates so that’s why I’m thinking of doing the drastic option. I don’t have any really fragile or expensive animals anyways.

 

[Alpha_and_Gec]

Check your test kit and do 50%. You definitely don’t want to go from 80 to 0 nitrates. Ever. Nor do you want to go below 20 anyways . Just my .02

yeah api kits aren’t the most reliable, but testing tap water vs tank water had shown a big difference in nitrates and algae growth is through the roof. I really just want to get it low enough such that I can feed the corals and add new fish again since the tank has been bare for a while now.

 

[Alpha_and_Gec]

Check your test kit and do 50%. You definitely don’t want to go from 80 to 0 nitrates. Ever. Nor do you want to go below 20 anyways . Just my .02

yeah api kits aren’t the most reliable, but testing tap water vs tank water had shown a big difference in nitrates and algae growth is through the roof. I really just want to get it low enough such that I can feed the corals and add new fish again since the tank has been bare for a while now.

 

[Alpha_and_Gec]

ah dang my ****** wifi duplicated one of my posts
how’d I delete this?

 

[Fishy888]

Oh right, forgot the most basic info lol
80 gal display tank, filter setup is mostly biological with a skimmer and a colony of caulerpa algae covered in filamentous algae. I used to change very small amounts very often to compensate for the lack of a large container, but that never worked to deal with this level of nitrates so that’s why I’m thinking of doing the drastic option. I don’t have any really fragile or expensive animals anyways.

You’ll want to drop your nitrates slowly, like 20 ppm per day. I’d do a 25% water change and retest.

That said, try getting your water tested at a LFS that doesn’t use API. If you truly have nitrates that high you’d have so much GHA you’d be able to mow it or make a sweater out of it, assuming your phosphates haven’t bottomed out. I’d try getting a Hanna nitrate high range checker. Salifert would also be good if you can’t get the checker.

Do you have chaeto in your system? Chaeto and xenia are nitrate eating machines. I like to keep them in my sump/fuge. They’ll take off in your system with adequate lighting.

The xenia and/or chaeto are just part of the picture though. Keep changing out enough water each day to drop nitrates by 20.

Once nitrates are at an acceptable level the chaeto and/or xenia will help you keep nitrates under control. Also try feeding a little less . That’ll help too.

 

[Alpha_and_Gec]

You’ll want to drop your nitrates slowly, like 20 ppm per day. I’d do a 25% water change and retest.

That said, try getting your water tested at a LFS that doesn’t use API. If you truly have nitrates that high you’d have so much GHA you’d be able to mow it or make a sweater out of it, assuming your phosphates haven’t bottomed out. I’d try getting a Hanna nitrate high range checker. Salifert would also be good if you can’t get the checker.

Do you have chaeto in your system? Chaeto and xenia are nitrate eating machines. I like to keep them in my sump/fuge. They’ll take off in your system with adequate lighting.

The xenia and/or chaeto are just part of the picture though. Keep changing out enough water each day to drop nitrates by 20.

Once nitrates are at an acceptable level the chaeto and/or xenia will help you keep nitrates under control. Also try feeding a little less . That’ll help too.

I did, in fact, accumulate enough hair algae over the past few months to probably make a mitten out of. I don't prune often because the damsel and hermits love it, and they don't pose a threat to anything. Chaeto's in a basket in the fuge, it kinda got overgrown with hair algae and got quite matted because I have no idea how to get that stuff off. Also, for your information, I have not fed this aquarium(or added anything other than filter media, caulerpa and some bacteria cultures) in close to a year.

I'll see if I have a separate kit for nitrates, used to have a few boxes from salifert(?) for calcium, phos and alk. No clue if it includes nitrates but if it doesn't I'll get one. I'm sick of losing api test tubes anyways.

 

[Alpha_and_Gec]

righty, no red sea or salifert nitrate tests, but I found 2 boxes of aiptasia - x for whatever reason. My plan for today is heading over to my lfs and either picking up a new test kit or having my water tested there after my family finishes with the day trip, and then pick up my new water change equipment(I used to just lug buckets around, with these new containers I have to get a pipe and pump). I'll decide how much water to pump tonight but 40 - 50% sounds like a reasonable amount.

 

[Alpha_and_Gec]

This is how the hellhole looks like btw, lots of coral skeletons, lots of hair. It usually looks better during the night when the leather is open. Turns out the dude with the pipes I need is out of the country today, so I'll need to proceed with everything tomorrow. I'll pick up the pumps today.

Tbh, the tank is entirely fine and stable as is, but I'd like to feel the joy of feeding and introducing new animals again. I've been wanting a Gymnothorax richardsonii and Cirrhoscyllium expolitum for a long time, although the latter is going to need some preparation lol.

 

[Alpha_and_Gec]

righty, update - one week after the water change, we've gone down to roughly 50 ppm. going for another one this weekend. nothing has died.... yet.

 

[Clanger]

This is how the hellhole looks like btw, lots of coral skeletons, lots of hair. It usually looks better during the night when the leather is open. Turns out the dude with the pipes I need is out of the country today, so I'll need to proceed with everything tomorrow. I'll pick up the pumps today.

Tbh, the tank is entirely fine and stable as is, but I'd like to feel the joy of feeding and introducing new animals again. I've been wanting a Gymnothorax richardsonii and Cirrhoscyllium expolitum for a long time, although the latter is going to need some preparation lol.

If you can get the rocks out ,get them in a bucket and give them a good spray with hydrogen peroxide and let them bake for a good while and then cover them with tank water till they stop fizzing and scrub with nail brush ,the rest will die off in the tank ...boiling hot water is super effient but will kill everything on and in its crevices .if they can't be moved use electric tooth brush ,like this ,will rip it off .. THEN do your water change and get your filter pumping ,ps I use a small net to catch the bigger chunks mid water .