Nitrate/phosphate Help!

[corey.nolta]

So I have been trying to improve my tanks overall health. It hasn't been bad, but there is always room to make it better. My biggest focus has been trying to get more color and growth from my corals. As the majority of them are pretty dull and slow growing.

My main focus has been the nitrates and phosphates. I have been in the salt water world going on a year now, and since day one I have always had issues with my nitrates and phosphates. Nitrates have hovered around the 15-20ppm with phosphate sitting at .25. Those are the lowest I have ever gotten them.

About three weeks ago I started dosing vodka in hopes to lower both levels. I have seen no change. On top of dosing daily vodka, I also run GFO, do 30-40 gallon water changes twice a month, and have a fuge with a good amount of chaeto. So my question is, what am I doing wrong that I cannot lower my nitrates and phosphates?

I did test the water in my holding container and it tested 0 for both, so it's not the ro unit filters or the container leaching. I change out my GFO every month. I even took a shot of vodka to make sure it wasn't diluted and was still in fact vodka I don't feel I overfeed, sometimes I wonder if I actually underfeed.

Any advice would be wonderful!
Here are some tank/livestock specifics

Livestock:
One spot fox face x1
Yellow tang x1
Blue/Green chromis x5
Ocellaris clowns x3
Tomato clown x1 (in sump)
4 Stripe damsels x2
Coral beauty x1
Lawnmower blenny x1
Blue headed wrasse x1
Spiney blue lobster x1
Various CUC

Tank:
90 gallon w/ 40 gallon sump
165w Chinese LED units x2
Reef Octopus 150
Carbon and GFO reactor

Parameters: (just tested this morning with a mix of Salifert and API products. Yes I know API isn't the best out there)
Ammonia 0 ppm
Nitrite 0 ppm
Nitrate 15-20 ppm
Phosphate .25 ppm
Calcium 440 ppm
Alkalinity 9 dkh
Magnesium 1500
Silicate .03
Salinity 1.026
PH 8.0
Temp 75

THANKS A TON!

 

[Greatreefer]

first off, what types of corals are you keeping?

What API test kits are you using to test for what? In the past, I've used API testing kits and have done side by side comparisons with API and the ELOS test kits. IMO I stay away from the API test kits because I personally don't like having to match colors with numbers. I'd rather have numbers and do calculations to get the readings. Also, sometimes the API test kits (if expired) will sometimes not give accurate readings. That's why I prefer to go with test kits that give you numbers rather than colors. In the end those kits do cost a little more but, you get what you pay for.
If I were you, I'd take your water into a LFS store and have them run tests for you and then take those readings and cross reference them against yours to see if your test kits are accurate.

In regards to nutrient levels you said in the post that you have a fuge with Chaeto in it? Are you also running a DSB and have you tried different types of macro algaes?

Also, what type of salt are you using?

On a side note:
I've been doing some research on natural filtration methods and using Pulsing Zenia in conjunction with DSB's, mangrove trees and other types of macro algaes to help regulate nutrient levels in a tank.

 

[corey.nolta]

I am keeping a mix of sps, lps, and softies. Mainly softies and lps. Can't remember the names of everything.
Softies; red shrooms and zoos / palys. Lps; Duncan, chalice, few blastos, torch, frogspawn, galaxia. SPS; green digi, hydno, birdsnest, caps
The majority of the test kits are API. Again, I know they are not the most accurate of test kits, I'm just trying to finish them off before buying new. They have not expired and I did test water from storage container as comparison, and it tested zeros. As far as taking it into the LFS, I only have petco and it is a terribly ran one.
In my fuge I am not running a dsb, as with the way the baffles are set up, I cannot run any type of sand bed. The only macro I have tried is chaeto.
I have been using Instant Ocean for salt.
I'll have to look into some other macros. What kind of lighting do other need? I am just running a standard light over fuge

 

[sc50964]

The large monthly WCs should have noticeable results in NO3 reduction, unless your bioload is very high. How often and how much do you feed your corals and fish? Have you checked your NO3 level right before the WC? You can also try adding chemical filtration like seachem Purigen but it is unusual that you NO3 is that high given what you've done to lower it.

As to your PO4 level, this has a direct correlation to waste from livestock and food. It sounds like you know what you are doing so I'm ruling out the usage of non RODI water to top off. So let's hear about your feeding routine.

One last thing that could be a possibility is the size and efficiency of your return pump. If your return pump isn't rated for your system, then it's likely that all these sump located filtration just aren't being exposed to the total water volume fast enough.

 

[corey.nolta]

That is correct, I do use Rodi water for my top offs.

When it comes to feeding, I feed once a day in the morning with lrs reef frenzy. Quantity is hard to specify. I feed enough for all the fish to get some with a little left over to circulate the tank for the corals and crabs. The piece I break off is about a 1"x1" chunk which is thawed in tank water and then put in the tank. I'd say I add a nice size piece of nori about once or twice a week as well.

As far as my return pump goes, it's a mag 9.5 pump with maybe 2.5' - 3' of height in return pipe.

I think I mentioned it in the original post, but this is nothing new. I've been battling this since day one. I've never had terrible algae problems bc the levels aren't sky high, but they are which enough to give me that fuzzy look and just be an annoyance. That and slow growing dull corals

 

[Bdog4u2]

With 17 fish in a 90 gallon you will fight nitrates. How much rock you got?
I battled high nitrates when I got in the hobby for awhile then all the sudden they were gone. When it comes to dosing it can take a good while to build up the bacteria it took me 6 weeks in my newest set up

 

[sc50964]

You certainly aren't over feeding, and the return pump is more than plenty at about 10x the water volume. So it sure looks like there aren't enough denitrifying bacteria in your system to keep up with the bio load. With a system that has approximately 100 gallons of water, you are changing 60% to 80% of water per month. Normal standard calls for 10 to 15% a week, or 40 to 60% a month. So there certainly is a case where you are exceeding the norm and perhaps you are just changing out too much water. Fish certainly wouldn't mind that since NO3 and PO4 aren't affecting them and your NH3 is at 0, but this much WC may just be too much of change for your corals. It wouldn't be hard to test out that hypothesis. Just do less WC and let that go for a month to see if things improve.

You might want to consider adding some denitrifying bacteria like what's in brightwell microbacter7. I've had good success using this to quickly set up tanks.

 

[Randy Holmes-Farley Verified Community Expert]

Bear in mind that nearly all of the N and P in foods ends up in the water as nitrate and phosphate, whether it is eaten or not. The goal is to just make sure that export matches the input from foods.

There are many ways to reduce N and P, and there's no reason to use just one (in fact, there can be good reasons to not do so).