Large water changes input
 

Tested my tank water recently, since this is something I've often neglected - and finally got most of the parameters inline except Nitrate (just did a 20% water change last week).

After searching the internet and other reputable forums water changes are the solution. Right now I have 80-160 ppm Nitrate which caught me by surprise - but it all makes sense now since two of my fish have disappeared in the last 10 days (cant find them, even after moving rocks, anemone likely cleaned up).

Large water changes are frowned upon, is this because most people are scared, and don't have experience and just carry on the myth? One article suggest draining tank down to 20% water - then filling up to 40% , then drain that down to 20% again, then fill back up. This theoretically would change my Nitrate from 160 down to 16ppm.

Anyone else had to resort to this? If it was an option - I'm concerned about corals being above surface water.

Look forward to your comments

water changes
 

why not do 10 % water changes every day for the next few days or twice a day.as for nitrates build a nitrate reactor

Water changes are not the most cost effective solution for high nitrates unless you have a nano.

What size tank do you have?

I would consider carbon dosing to lower nitrates if you have a good size tank and skimmer that is oversized.

this is a 90 gallon tank

the problem with 10% water changes, it would take 22 consecutive days to get Nitrates from 160 down to 16 (theoretically) provided nothing else impacts the levels

That's assuming your nitrates don't continue to climb / increase along the way via heavy feeding etc.

The first course of action would be to find out what's causing your high nitrates and then come up with a solution and path forward. You don't necessarily want to drop your nitrates that far that fast, nothing good happens fast.

As important as water changes are...they are not a great way to reduce nitrates. there are many ways to reduce nitrates as mentioned above but i think you also need to find the cause of the nitrates. perhaps the two dead fish caused the spike or maybe the deaths were caused by the high nitrates. change some water and look into one of the nitrate reducing methods.

Since it's to the point where there are casualties, it might be a good idea to try and reduce the nitrates fairly quick.

I would perform a 20% water change every 2 days until the nitrates are in check. During this time look for the cause of the nitrates and look into a long term solution for the nitrates.

If you want some solutions, it might be a good idea to post some details about your setup / husbandry.

90 gallon reef tank with one corner overflow & opposite side return, (2) 950 gph powerheads. Estimate 75lbs Live rock with fine sand bed.

-estimate 30 gallon multi chamber sump with:
-Marineland Pro 300 skimmer first chamber with return line - no filter sock
-one free chamber with heater and sensors
-Sedra 7000 return pump in last chamber with nano sized powerhead to keep circulation in sump & ehiem canister filter acting as a reactor filled with the red ceramic balls, introduced this when trying to seed zeobak

P.H. around 8.2
Temprature 80.5-81.5
Magnesium 1100ppm-1300ppm

I'll get my other readings when I'm at home tonight

Agreed, I only meant for a very large water change, 80% etc.

If the fish are already stressed from the high nitrates, adding in the stress of acclimation to a very large water change isn't the best option, unless you have no choice. In which case, you do what you have too.

I would have no concerns doing a 80% water change. Just be sure it's very close to the existing water in all parameters you can measure. Temp, pH, Ca, etc..And don't use a different salt :)