How do I lower my nitrates

My nitrates are at 40 ppm and it seems like they wont come down I don't know what is causing them. I have been doing a 10% water change every week except the last couple that where like 20 and 35% and it still didn't drop at all. All of my corals seem the be happy except for my devils hand.
i have a ten gallon with a pair of clown fish and 2 snails  and 2 crabs  i usually feed the clowns once a day. I have  about 10 lbs of live rock in there and a hang on the back filter. the corals i have are zoanthids, gsp, hammer, candycane, frogspawn, kenya tree, xenia. I also have a rbta and i seems to be doing fine I just don't want to kill everything nothing is showing any bad signs but i am not going to take and chances. could i be the filter sponge in the hob filter i usually rinse it out when i do a water change?

My Tank has been set up for 7 months now  I will try feeding less.  i usually feed flakes and i usually only feed them as much as they can eat in a couple of minutes. The hob is an aqua clear so has a foam insert, carbon and bio media i also have a small piece of live rock in there. all the snails i add die even when my nitrates where like 5-10ppm the always die with in a couple of week and i can figure that out either.

for dying snails, I'd check your phosphate levels, go to your LFS, have them check to see where it's at. I be that is one source of the problem.Or super hungry hermies. I'd also cut back on feeding. Honestly they'll eat till they explode. I feed mine 3times a week. What size is your tank? 

I know exactly what it is. I've seen this many, many times. I'm going to go through of lot of new information here, but if I don't write it all at once here as I think of it, I may later forget to cover it, so here goes. You may need to read this several times. It's stuff that I have learned over the course of 20 years in this hobby.

Remove the sponge and never use it again. It is a "nitrate factory". The bacteria living on the sponge are creating more Nitrates than the sand bed can handle.
The bottom area of the sand bed changes Nitrates into Nitrogen gas and water but it's not able to keep up with the production of Nitrates from the sponge .
Bioballs are the same type of Nitrate Factory. That's why we don't use them anymore in reef tanks.

The Aquaclear HOB(hang on back) filter's best purpose is to run AC(Activated Carbon) for 2 weeks of every month. AC gets used up in 2 weeks so it's good to remove it after that. The additional water flow from the HOB filter can be helpful, or just remove it for 2 weeks and let it dry out.

Also, 10% monthly water changes are all that's needed. Any more than that, as you have seen, is a waste of salt and effort.

The biofiltration takes care of pollution (Ammonia, Nitrites and Nitrates). FYI, a 20% water change reduces pollution by only 20%. It's not worth the effort, when biofiltration can do the job so much better and quicker. Two of the components of biofiltration is algae and the coral's zooxanthellae algae. Algae eats up pollution like crazy.

We can discover why snails die. Let me start by asking a few questions:
Is there a cover over this tank?
What is the depth of the sand bed?
Where did the rock come from?
Besides AC, what other filtration media has been used?
May we see a pic, even just a cell phone pic will do. (If you can't post it here, send it to [email protected] for me to evaluate)

Please feel free to ask more questions here and also look at the WMAS Reefkeeping Tips linked in my signature line below.

Here are just two of dozens of small tanks I have had over the years. Note that it's difficult to see the powerheads that create the main water flow. They are hidden on the bottom, behind the rocks, pointing up. That kind of flow is the best for creating a healthy tank.

Above - One powerhead is hidden behind the rock with the large Toadstool Leather. This was WMAS Tank of the Month for July 2003.

Below - powerhead is totally hidden at the bottom back center, shooting straight up. You can kind of see the wave action it created at the water surface. The HOB filter ran AC for only 2 weeks/month on this 9 gal reef tank.

I had a smaller tank just like that once. I used the HOB filter to run chaeto in with a small light over it. When I thined the chaeto I would put a bag of AC in for a couple of weeks like Mark suggested and pulled it out to let the chaeto grow some more. I kept my nitrates quite low using this method. I also added some oolitic sand for a deaper sand bed. Good luck.

Yes, that's exactly it. Though not necessary, a Refugium is always a good thing.

Thanks for the pic. The tank looks very good. Coral are the indicators of problem Nitrates and since these coral look good, Nitrate pollution is not a problem in your tank. It may also be that the test kit/strip is reading a little high.

I can confidently say there's no need to do any extra water changes, other than 10% monthly.

That Biomax filter insert is probably another reason for the high Nitrates. I would discard that too. Now that I know you have both a sponge and Biomax, remove one now and the other in a week. The reason for this is that removing them both at the same time may be too much for the current biofiltration. It's always best to make changes slowly.

The biofiltration which is continually growing and developing in the LS, LR, LW and algae is more than enough to properly filter this tank. My one suggestion here is to add some Macroalgae. Caulerpa is beautiful. You can see several varieties in both of those pics above. It adds to the biofiltration capacity. Algae eats pollution like crazy. It also adds beauty, color, shape and movement.

The LS depth looks sufficient to me, especially since it appears to be Oolitic sand, which requires less sand to do the same job.

Coral open and close so don't be worried if one is temporarily closed for a week or so.

I would suggest moving that powerhead down behind the rocks, turning it sideways and swiveling the nozzle so it shoots up vertically or diagonally at the water surface. I would also remove the fan attachment, unless the single stream shooting up splashes water out of the tank. This type of water movement disperses the oily film that is accumulating at the water surface and is ideal for tank health.

Regarding the film, one neat trick I learned years ago is that it can be removed periodically with a paper towel or a sheet of plastic food wrap. Set the paper or plastic flat on the water surface, immediately grab it in the center, lift it up and throw it in the garbage.

The thin oily film on the water surface is restricting "gas exchange". CO2(Carbon Dioxide) and O2(oxygen) are dissolved in the water. When the extra CO2 cannot leave and O2 cannot enter the water because of the film, the water's pH lowers from it's ideal of 8.3. pH as low as 8.0 isn't so bad during the day, but at night when algae stops using CO2 and uses O2, the pH can fall below 7.9 which is an unhealthy level. The day to night pH swing is a cause for stress on all the organisms. This could be one of the factors of the snail deaths.

I see that the tank is covered by the light fixture and the lid. I would remove the lid immediately. This is further restricting gas exchange and making pH low.

With a light hood like that, I cut off the frame where the lid sits and also remove the glass cover. If it fits on the tank, the light housing can be set right in the lip of the aquarium frame. I sometimes move the light fixture forward, closer to the front, to better illuminate the animals. The glass partially restricts light from reaching the coral, especially as a salt layer builds up on the glass.

Another factor in snail deaths could be the rock. Where did it come from

One last item that I just realized. I rarely use a heater. It's summer in Utah. A heater is not needed. If the water stays between 70-80 the tank does just fine. In fact, in Winter, if the tank is in a heated room and not too close to a draft, a heater isn't needed at all. Heaters usually stick in the ON position and a heater of that wattage would cook your tank within an hour. (I actually place my tanks in windows whenever possible. Sunlight is awesome. It grows everything like crazy and there's nothing like the look of a reef in the morning sunlight. )

I know this is a lot, but it's many of the things I've learned over the years of keeping hundreds and hundreds of tanks. Take it for what it's worth.

A simple screen top solves the jump and gas exchange problem, as far as the anem goes if its happy increased flow so long as its not direct flow will not bother it and it will improve your tanks health. simple math how much water you have vs how much flow . I have a 72 bow that turns the water at 3700gph yes it is sps dominate but my anem has only ever moved 4 inches when i redirected my flow .and i still think i need more flow but based on you coral selection is the determining factor. as far as chateo growth it is my understanding that if it was on reverse lighting it would grow way faster as when its lights of and lights on in the fuge it is way more effective to exchange co2 etc when you tank is idle at night . its growth is judged on what it can eat, so there is less food during the day because all are in competition. in a fuge its pretty much eating everything while others sleep . so no fuge = less effectiveness way more complicated than that but its a simple idea . correct me if im wrong to all who are reading this .

i setup a fishtank using discount live rock from lfs and it was a mess i faced the same problem high nitrates i had a great skimmer and sump systm but i could never lower my nitrates. Come to find out it was the live rock causing the problem.

The light i have been using is like a standard hood except it is just 1 t5 instead of  1 t8  and i have been waiting for my new lights to come for like two weeks then i will have 4 t5 on there.

what kind of lights did you use on your nano Mark?