NO3 problem

[inspire0522]

hey guys... ok so after my cycle was over i did a 35% PWC. No3 was at 20ppm so i did another PWC 20% a day later still 20ppm. Checked a day later and was still at 20ppm so i did another PWC 20% today. Checked for No3 tonight and still at 20ppm! Everything else seems fine Nitrite 0 Amm 0 SG is 1.023 PH is a little low but not that bad 7.8. So now what, more PWC or am i missing something? If so i need more salt
51gal
70p LR
60p LS

 

[ColdFish]

Are you running a canister filter? I was having a similar problem, couldn't get my nitrates to go much below 20 until I finally ditched all the media in my Fluval. I didn't dump it all at once though. First I removed the foam inserts, then about a week later I pulled about half of the bio-beads, then another week and I got rid of the other half of the beads. I read someplace that all of that stuff actually works against your liverock. Seems to be so as my 50 gallon is a lot better now. I still run the Fluval for the circulation and to run carbon in sometimes.

 

[tecwzrd]

Most no3 tests have that range jump from 10 ppm to 20 ppm and determining that range isn’t always easy. Doing 20% each time is going to see very minimal reductions in no3 but is ok for maintaining lower no3 levels.

Just because your tank has “cycled” doesn’t mean that there isn’t still an nh3 source still in the tank which would be unreadable with an nh3 test kit because the bacteria are still converting it to no2/no3.

When you first did your 35% what was the no3 reading before and after? You will have to do 3 50% pwc to get it to 0 ie: first 50% cuts the 20 to 10 ppm, second cuts the 10 to 5 ppm and the last 50% cuts it to 2.5 ppm or much closer to 0.

For a FO or FOWLR I’d at least get it down to 10 ppm or less and keep performing 10%-15% PWC each week for the first 6+ months until your lr/ls has had time to establish facultative bacteria needed to keep no3 low naturally.

Also as ColdFish stated if you have a HOB/sump/canister and have filter media that is trapping waste that will also work as a nh3 source and keep your no3 high. That’s why it’s best to replace with lr rubble or run empty as I do unless using GAC or other media for a short time.

Rinsing the filter media off every couple of days or weekly helps keep your no3 down but eliminating them from the equation is even better.

 

[malkore]

also, test the water you're putting back in. maybe its not as pure as you thought it was.

 

[inspire0522]

thanks for your help guys
I removed my fluval after the cycle. Im not sure what the No3 was before the first PWC 40 - 100ppm hard to read that thing! I did check the water that was going into the tank, was 0ppm ( ro/di). I guess more PWC are needed. Should they be more then 20%? What salt mix do you guys like best? Im do for some more today.

 

[tecwzrd]

I guess more PWC are needed. Should they be more then 20%?

Even with fish/inverts properly aged SW (mixed for 24 hours with a ph and brought up to tanks exact sg/ph/temp) in PWC quantities of 50% is pretty safe if slowly added to the tank. If you do not have any fish/inverts yet then I wouldn’t even think twice about doing a 50% PWC.

By doing 20% changes it will take you much longer to reduce your no3 and will only waste time. For example your no3 is at 20 ppm and below is what happens when you do 20% pwc.

1st PWC: no3= 20 ppm * .2 (20% PWC with 0 PPM no3 water) = 4 – 20 ppm = 16 ppm
2nd PWC: no3= 16 ppm * .2 = 3.2 – 16 PPM = 12.8 ppm
3rd PWC: no3 = 12.8 ppm * .2 = 2.56 – 12.8 = 10.24 ppm
4th PWC: no3 = 10.24 * .2 = 2.05 – 10.24 = 8.19 ppm
5th PWC: no3 = 8.19 * .2 = 1.64 – 8.19 = 6.55 ppm

By now you have mixed 50 gal of SW (10 gal for a 20% change) but still only reduced the no3 down a little over 13 ppm less and had to mix and add 5 times. That’s not even including how much no3 built up over the time it took to do 5 PWC.

If you mix 75 gal of SW total and perform 50% PWC (about 25 gal) every day for 3 days you will have no detectible no3 when finished.

What salt mix do you guys like best? Im do for some more today.

Consistency is more important then the actual brand used along with maintaining ph/sg/temp in the tank and when doing PWC. Some of the more readily available brands are:Instant Ocean, Oceanic, & Red Sea. Higher quality salts would include: Tropic Marine Salt, Kent Sea Salt, & Crystal Sea Marinemix which are better formulated for reef tanks.

 

[inspire0522]

wow.. thank you for the info! I will do that, going to need a few more buckets! well.. on my way to LFS. Im going to try and resist the urge not to buy anything else but the salt mix

 

[Brenden]

Im going to try and resist the urge not to buy anything else but the salt mix

I feel your pain

 

[ReNNie]

My NO3 were around 10 so I tossed my bio-mass but left the foam and about a week later after my regular 10% (weekly) water change they are up to 20 now. Should I toss all the foam as well? I thought the pads sort filter out all the particles in the water? Any help would be great Thanks Matt

 

[seaham358]

how about making sure the test kit is good.. and did you test the fresh water your using? A 20 is not the end of the world and its higher then wanted but not pushing the limits.. So don't kill yourself trying to hit the magic number of 0.. take your time to enjoy the hobby some..