Where Are These Nitrates Coming From?

[Jandrix]

Hi Everybody,

This is my first post but I've been a long time lurker on the site, I've finally decided to ask for advice regarding my 35G Hex FOWLR setup.

The problems is the nitrates in the tank rise extremely quickly, from all the testing I've done I've determined that they will rise about 15ppm every week, i.e. if I'm at 0ppm on day 1 I'll be at 30 ppm on day 14 which is impossible to control even when doing big water changes weekly.

Tank Info:

35G Hex
50 lbs live rock
1" shallow sand bed that is stirred weekly
1 Maroon Clown, about 3" long
1 Trochus snail (the other inverts have all slowly died off from the high nitrates but this snail seems to be invincible as he's about two years old).

pH 8.2
ammonia 0ppm
nitrite 0ppm
nitrate 60ppm
temp 78F
salinity 1.025

Equipment
JNS VS-1 skimmer, I get light yellow skimmate with brown muddy bits in it
Powerheads, 1 x 750gph, 1 x 425 gph
I used to have a fluval 204 canister but got rid of that because I thought it could be the reason for my high nitrates so I don't currently run a mechanical filter.
Lights are on from 10am to 9pm, just a basic halogen tube light.

I feed Lola (the clown) every two days with about 1/3 of a cube of Hikari Mysis shrimp and once a week I crumble up a square centimeter piece of nori and mix that in with the food. The food is thawed in tank water and then strained in a net before being added to the tank. I turn the power heads off during feeding but some food does seems to make its way down to the rocks, eliminating this seems to be my only course of action at this point because I don't know what else could be producing so many nitrates.

I've been trying to do lots of big water changes to get the nitrates low enough that I could add in some more inverts that might help with cleaning up uneaten food but the lowest I've been able to get them is 30ppm and then I unfortunately had to go on a trip for two weeks so they're now back up to 60ppm. I've got 15 gallons of water mixing currently for a water change tomorrow. I should also mention that I use RO/DI for my water changes, not tap water.

So please give me your opinions, I've battled this issue since the tank was set up about two and a half years ago and the constant work with no change is really discouraging and making me consider taking it down.

P.S. I've had the tank water tested at my LFS to confirm the nitrate readings, although last time I did this was a year ago so maybe I can try again just to see if my API kit is giving me false readings.

 

[Jandrix]

Here's a picture of the tank after today's 15g WC.

 

[gunther13mt]

Surprised no one has answered you yet. Sorry ive been off for awail but how was you rock cured. I had this problem for a long time and very recently just "baked" all my rock. And washed it. This has only been a few days ago that i got finished and all rock back in the tank but so far my nitrates are gone. Believe it or not our rocks can leach phosphates into the water.id suggest testing for that with your daily test and adding a GFO matrix if you don't already have one.

Sent from my VS880 using Tapatalk

 

[Jandrix]

Very interesting, I purchased about 30 pounds of "cured" LR from my LFS when I first set up my tank, I gave it a rinse in saltwater before going in the tank but didn't do any kind of baking or cooking. The other 20 pounds has come from pieces of base rock that I've added over time in hopes that I could establish from nitrifying bacteria to lower my nitrates. The base rock was soaked in RO/DI water for about a month before going in the tank.

I'll pick up a phosphate test kit to see what kind of levels I'm seeing and report back. I've also as of this week started feeding my clown with larger Mysis shrimp and one piece at a time so there is basically zero uneaten material entering the tank now. If this doesn't start to help then baking the rocks a few pieces at a time for a month or so will be my next course of action. I guess the only concern will be keeping an eye on ammonia while there is a reduced amount of LR in the tank in case the bacteria can't keep up, although with only one fish I don't see it being much of an issue.

 

[HarlequinAddict]

IDK if your rock needs to be cured, but what you can do for now is buy chemipure elite, (MAKE SURE TO WASH IT OFF UNTIL YOU SEE THE WATER IS CLEAR), and purigen. Purigen is an awesome product! I use it daily and removes all tank waste in just a few days.

 

[Jandrix]

I actually tried Purigen in my fluval 204 canister when I had it running and noticed very little difference, if any, in my Nitrate readings, maybe I was doing something wrong. I don't have the canister anymore so I don't really have anywhere to place filter media unless I could put it in the body of the skimmer...would that work?

 

[Jandrix]

Here's the tank for those interested.

 

[caribfan]

Nice looking tank and welcome btw.

So I'm going to go into a couple basic things and if you all ready know this, please don't take it as me talking down to you, it's certainly not my intent.

So my first point would be, if you aren't going to keep SPS, I wouldn't be overly worried about nitrates in the 30 - 60 range. I'm not a coral guy, but I know some of the guys into softies/zoanthids and LPS actually advocate for some nutrient (nitrate) levels because it enhances colors. Again, not a coral guy, but I'm pretty sure I read that somewhere.

In terms of where are the nitrates coming from, that's easy. They are coming from the food you feed. The basic nitrogen cycle is this:

Food enters system, is eaten by your fish and turned into detritus (poop) or uneaten food decomposes and turns into ammonia.

Ammonia is rapidly broken down by naturally occurring bacteria into Nitrite and then Nitrate. Thus, the more food you feed, the more nitrates you will have.

Typically we deal with nitrates in a couple different ways. The most basic way is to dilute the nitrate concentration in the tank via water changes. If you've got a 100 gallon tank with a nitrate concentration of 100 ppm, a 50% water change will yield a new nitrate level of 50 ppm.

Big water changes are good for knocking down high concentrations, but you can obviously see the law of diminishing returns as the concentration gets lower, i.e. for a 100 gallon tank with a nitrate concentration of 1 ppm, a 50% water change would only reduce the total nitrate concentration by 0.5 ppm.

So the question is how do we manage nitrate concentrations if our tanks require it.

There are a couple popular methods you can look into and I'll list them here below:

1. Cheato algae. This is essentially keeping some nitrate and phosphate consuming algae in your sump and harvesting it as it grows and consumes nitrates.
2. Algae turf scrubber. A more controlled and advanced means of using algae to consume nitrates and phosphates. Some people swear by these and I think they probably do a good job if the starting concentration of nitrates / phosphate is low.
3. Sulfur denitrators. Don't know much about these other than they rely on a anaerobic bacteria to synthesize the nitrates.
4. Vodka/vinegar dosing and Methanol Reactors. This is a pretty cool method utilizing vodka, vinegar or methanol as a means of fulfilling the Carbon quotient required to meet something called the redfield ratio.

I would suggest utilizing this site to learn more about each of these methods and determine which will best fit your tanks needs. If you don't have any intentions of having SPS, I'm not sure I would be worrying too much about nitrates.

Hope this was helpful and not confusing.

 

[caribfan]

Very interesting, I purchased about 30 pounds of "cured" LR from my LFS when I first set up my tank, I gave it a rinse in saltwater before going in the tank but didn't do any kind of baking or cooking. The other 20 pounds has come from pieces of base rock that I've added over time in hopes that I could establish from nitrifying bacteria to lower my nitrates. The base rock was soaked in RO/DI water for about a month before going in the tank.

I'll pick up a phosphate test kit to see what kind of levels I'm seeing and report back. I've also as of this week started feeding my clown with larger Mysis shrimp and one piece at a time so there is basically zero uneaten material entering the tank now. If this doesn't start to help then baking the rocks a few pieces at a time for a month or so will be my next course of action. I guess the only concern will be keeping an eye on ammonia while there is a reduced amount of LR in the tank in case the bacteria can't keep up, although with only one fish I don't see it being much of an issue.

One quick point here, I would not advocate baking your rocks. You will still have nitrates, even if there is no wasted food in the tank. As i mentioned in my last post, fish poop, is still ammonia, which breaks down into nitrite and then nitrate.

Not a bad idea to minimize uneaten food, but you'll still end up with nitrates.

 

[Jandrix]

Thanks for the info Matt, I'm a few years into the saltwater side of this hobby so I'm aware of most of what you're saying but it's nice to have a clear summary of what's happening.

My main reason for wanting to bring the nitrates down is to be able to keep inverts, with the current levels (aside from my super snail) most snails / shrimp / crabs that I have added to the tank only last 6-10 months and I believe the higher nitrate concentration is to blame for this.

I've read about chaeto harvesting, reactors, and vodka dosing and I'd be willing to try one or all of those methods. I guess my issue is that I want to understand why MY tank is behaving this way when I regularly read about FOWLR tanks that are the same size as mine, with heavier stocking, and fewer water changes having much lower nitrate levels, I can't get away from the thought that I MUST be doing something wrong when there are so many examples of tanks that don't have my issue. I'd like to try to get the levels down without using what I view as a Band-Aid solution i.e. chaeto / reactors / vodka dosing, maybe this is unrealistic though and you folks can set me straight!

 

[gunther13mt]

My nitrates always test high with API i have 3 cleaner shrimp, 4 emerald crabs, and an anemone they are all fine as my real nitrates are about 40 lower thanthe test show. Confirmed by other test and my LFS. Just food for thought API has issues with that test.

Sent from my VS880 using Tapatalk

 

[Jandrix]

Is there a more trusted / accurate brand of Nitrate test that I could try for comparison?

 

[gunther13mt]

Sailfert, red sea and hannah are all good brands Hannah is the most expensive but red sea or sailfert will work perfect pretty accurate.

Sent from my VS880 using Tapatalk

 

[caribfan]

Is there a more trusted / accurate brand of Nitrate test that I could try for comparison?

I like Elos as well.

FWIW, I've kept skunk cleaners and fire shrimp in a tank with 80 +ppm for a long time with no issue.

I also wouldn't call those methods I mentioned above a band aid; I consider them more of a management strategy.

I don't see that you're doing anything wrong. Proper skimming will help reduce the amount of nutrients available to be turned into nitrates.

Look into methanol denitration on this forum, it's the most unique option out there in my opinion. I've thought about installing one in my 240 before, just haven't had enough time

 

[Jandrix]

I did some more reading today and I think I'm going to go with the following plan:

1. Purchase a higher end Nitrate test kit (my LFS has the Red Sea in stock) and a
phosphate test kit.
2. Continue hand feeding every other day to reduce waste as much as possible.
3. Monitor Nitrate + PO4 to see if there is a reduction in the rate it accumulates.
4. If I don't see an improvement I'm going to start vodka dosing (after the required
research) this seems like the most economical solution for me at this time.

 

[caribfan]

I did some more reading today and I think I'm going to go with the following plan:

1. Purchase a higher end Nitrate test kit (my LFS has the Red Sea in stock) and a
phosphate test kit.
2. Continue hand feeding every other day to reduce waste as much as possible.
3. Monitor Nitrate + PO4 to see if there is a reduction in the rate it accumulates.
4. If I don't see an improvement I'm going to start vodka dosing (after the required
research) this seems like the most economical solution for me at this time.

Do some reading up on the red field ratio and how/why vodka dosing works. If you are kind of a nerd like me you'll probably find it really interesting.

Dosing any of the carbons sources like vodka and vinegar will drastically change your skimmate too, so be sure your protein skimmer is a good one.

 

[Jandrix]

The JNS VS-1 I have is rated for 75 gallons and skims very well, should that be sufficient? The tank is 35 gallons.

 

[caribfan]

The JNS VS-1 I have is rated for 75 gallons and skims very well, should that be sufficient? The tank is 35 gallons.

Honestly don't know much about it, not a brand I'm familiar with.

If you are getting pretty good skimmate I'm sure it's sufficient.

 

[Jandrix]

Just a little update:

On August 21st I did a WC that brought my nitrates down to 40ppm, on that day I also started skimming much wetter than before and I started hand feeding my clown with larger Mysis Shrimp, one at a time, to ensure no waste.

Well, as of yesterday, 10 days later, my Nitrates are still reading 40ppm, hooray! I'm going to hold off another few days before my next water change to see if they will still remain at 40ppm after two weeks, if so I think I've found my problem (over feeding mostly).