Nitrates didn't go down after water change?

Hello All,

I currently have a 75 gallon fowlr that has been running since December 27. I have not been able to get my nitrates below 20ppm. I know in a fish only tank nitrates aren't always that important of an issue, but I would prefer to keep them as close to 0 as possible. Every week I do a large 32 gallon water change as that seems to bring the nitrates down. After doing my water change this week, I tested and noticed no change in test results. I test using the API liquid kit. The tank is not heavily stocked, having only 2 clownfish, 1 lemon peel angel, 2 fire shrimp and a chocolate chip starfish. The tank has about 90 pounds of rock and 100 pounds of sand. Could it be that I have a bad test kit and am getting false readings? Thank you in advance.

 

those API test kits are notorious for inconsistent readings. I often run two test at the same time and get different results. Make sure you shake bottle 2 really well before using it. Also, sometimes there is detritus that accumulates behind rock that can build up in a system. You dont have a very large bioload so make sure you over feeding. 90 lbs of rock is PLENTY of rock for a 75g tank. and that is alot of sand. Just keep up with your water changes. If the nitrates stay high then you may want to re-evaluate your filtration and/or water change schedule.

 

Normally a water change that large is not necessary...
That tank is still a newish tank and I would say wait another month or two before making any big changes as the tank is still cycling. There is the stage for Ammonia and nitrite spikes then comes the nitrate stage. It will vary with every tank as to how long it will take to stabilize. As long as things move a long as normal the nitrates will come down unless you put too much food in the tank and don't have a proper method to export the nutrients.

 

+1^^^ such large water changes in a relatively new tank will mess with test results. I would suggest that you not chase the nitrates in a fowlr. Let your tank and inhabitants let you know if its problematic. I'm not suggesting that you not test but you can obsess about chasing numbers when in reality if your inhabitants look healthy and are eating and you're not getting algae or other blooms, you can sit back and enjoy your tank for a while

 

You can try and clean you test vials out with a vinager bath too. Maybe there's something in the vial.

 

I agree with the above, your tank is still very young and you will go through that. 20 ppm isn't that bad actually. My tank hovered at that number for about 3 months after the initial cycle before it went down to 0. That was with 5 gal water changes on a 55 gal tank every 2 weeks.

 

I would suggest salifert over API. I had been misled for a while using API.

 

First off congrats on the new(er) setup!! Read through stickies and old post here.

To your thread, a large waterchange like that every so often if stressful as all heck to your young system!! When I set up a 46gal I did 5gal weekly WC. Once in awhile I would up it to 10gal but thatd be rare. My nitrates werearound 10 for the first 6 months. The ammonia and nitrite consuming bacteria build up much faster than nitrate eating bacteria so it takes a lot longer for that final leg of the cycle to complete. You can add fish during that time but thats why you need to go slow and dont go sps acro happy until your system is established.

Your tank will go through many cycles and wont be considerign stables for the first year or so. Some say a little longer some shorter but a year is about the average. During this time you need to allow your tank to cycle normally to decrease issues down the road. I like happycorals threads and believe it was in one of them where there was a rant about long gone are the days of ultralow nutrient systems. ALL corals need some nitrate and phosphates and a 20 is a little on the high side for a mature SPS sytem, but for a new fish only system is nothing to concern yourself about.

Dont add any more fish until you start seeing a drop and continue to test frequently. API is known to be inaccurate but I use them all the t ime for spot checks. Ialso use a RedSea kit for nitrates and it works great, might want to upgrade and get a better kit so when you get numbers you dont like you can compare to see how accurate it is. I added xenia in my tank too which consumes nitrates better than algae IMHO. Grows like a weed and would grow on my hands if I left them there too long while pruning lol.