Does a sandbed help reduce nitrates?

sk8 · Sep 7, 2017

I have a 90 gallon BB tank with a ac110 that runs a sponge and cheato which I trim out a softball size clump every 3-4 days. There is roughly 70lbs live rocks. I have a jeabo 700 gph pump running along the bottom of the tank so there is little to no detritus settling a jeabo rw4 and a sicce 1320 near the top of the tank for surface movement. I also have a sea clone 150 skimmer (I know not the best but it pulls out a full cup of dark brown skimmate every 4 days). The tank has been set up since November 2016 it was an upgrade from my 50 with the same problems. My nitrate levels have been at the max with both API which was dark red and Red Sea which is deep purple. I do a water change every week of about 15 gallons. During a water change I turkey bast the rocks and syphon the detritus out of the ac 110. And feed my fish once every other day mostly spirulina flakes and occasionally brine shrimp.

Fish:
Blue tang 2"
Yellow tang 3.5"
Clown 1.5"
Royal dotty back 1.5"

The last few days I have been doing 15 gallon water changes daily with no change in the nitrate. A month ago I did a 70 gallon water change the nitrate went down to 40 and back up in a couple days. I tried vinegar dosing for 3 months with no change and read my skimmer probably isn't good enough so I discontinued dosing. I was ready to throw the towel in but I remembered a guy on another forum added sand to his tank because he had high nitrates. The topic was never updated to if it helped or not so I want to know what people's thoughts were before I went out and bought a bunch of sand

ccbobafett · Sep 7, 2017

I have a deep sand bed six inches and I think most of my filtration comes from it imo it requires lots of mainentce like stirring and vacuuming removing algae but worth it in the end. Good luck

saltyfilmfolks · Sep 7, 2017

In general not really. It does house more bacteria , but generally is a trap for detritus. Def get a double check on your nitrates. That just doesn't sound right. Maybe look for some build up of funk, would be my only guess.

ndrwater · Sep 7, 2017

The simple answer is no... But yes... Sorta. Maybe.

A sand bed may.... MAY help with Nitrate reduction in areas of stagnant/very slowly moving water through anaerobic activity.
A deep sand bed (like 4-6" deep) will definitely have anaerobic activity and definitely help with Nitrate reduction. Problem with a deep sand bed (DSB) is that in my opinion, it's a time bomb. The issue is if the DSB is disturbed, all that anaerobic bacteria and associated nitrogen gas is then released into the tank, more often than not causing a crash.
The reason many people went to bio pellets was to get around the probs of a DSB.
I am no fan of Bio pellets either, but they do work. Problem is you need to maintain the bio pellet reactor to maintain the reduced nitrates. You let things get away from you, you have similar results as a disturbed deep sand bed.
Carbon dosing (vodka etc) is similar to a bio pellet reactor without the reactor. Same idea as the reactor as you are carbon feeding a type of Bactria that use Nitrate as an additional food source. Probably the safest of the 3 options mentioned above, but also not without potential perils like wierd bacteria blooms being the ugliest, but least devastating.
I will make 2 suggestions.
A) double, then tripple check your test kit readings by having a LFS, friend with a different type of test kit, or even have an ICP test done to confirm your results. Nitrate tests are notoriously inaccurate.
B) do more frequent small water changes using a high purity water like RODI with a good quality salt.
Understand that Nitrate is the byproduct of the Nitrogen Cycle. Meaning you can't have Nitrate without first having Ammonia and Nitrite.
I would reevaluate your feeding schedule, protein skimmer and source water in that order.
Also know that many a reefer is now dosing Nitrate to help with Coral coloration. Chasing numbers isn't a great idea.
Best of luck

sk8 · Sep 7, 2017

Ok I will take a sample to my lfs to double check. I get all my rodi water from him as I'm renting so I don't really want to tap the pipe to set up my own ro. Thank you

ndrwater · Sep 7, 2017

sk8 said:
Ok I will take a sample to my lfs to double check. I get all my rodi water from him as I'm renting so I don't really want to tap the pipe to set up my own ro. Thank you

Not to try and irritate your LFS, but... Double check the water you are buying. More times than I care to count, water from the LFS is just filtered water that they add salt to. Nothing wrong with this at all, BUT..... If they don't maintain their RODI (making the grand assumption that IS what they use) as well as they should, your source water could contribute to the issue.