# Question on filtration



## new2hobby (Mar 14, 2009)

I started out with a 55 gallon FOWLR tank with 70 pounds live rock and 40 pounds live sand. I have an aqua clear 70 hob filter, 1 aqua clear 70 power head, 1 aqua clear 50 power head for water flow, and a coralife 65 skimmer. I added a 30 gallon refugium with an 4" sand bed and about 20 pounds live rock and caulerpa macro algae for nutrient export. I also have an aqua clear 30 filter on the refugium with the intake between the baffles. My nitrates still run between 20 - 40 ppm. My question is can I take out the filter media in the hob filters and let them run empty, just for flow, and that might help with the nitrate. Would I have enough filtration without the filter media? Any input would greatly be appreciated. THANKS!


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## AZDesertRat (Apr 10, 2009)

I don't think your filter media is helping with nitrate removal, if anything it may be making it worse by trapping stuff and supporting nitrates.
Your nitrate removal is going to be through a deep sand bed, good porous live rock and the macroalgaes in your fuge.
40lbs of sand in the display is probably not going to do much since a fully functioning deep sand bed needs to be in the 3-6" range an err on the deep side if anything. My display is a 100G, 60"x18" and 23" high so is not significantly more surface area than your 55 is but I have 330lbs of Southdown sand in it for a 5" DSB. The more surface area you have at the proper depth the better off you will be. The sand in the 30G fuge helps but it does not have a huge amount of surface area. Personally I would transfer more or all of it to the larger display and maintain macro algaes and maybe live rock rubble in the fuge.

The grain size of the sand is also important, the finer the better when it comes to supporting both bacteria and the beneficial fauna needed to maintain the DSBs integrity. You want to disturb it as little as possible, never more than 1/4 to 1/2" deep when vacuuming or cleaning and then only in small sections at a time. No sand sifting starfish! They are predators and will kill and consume every living creature in the DSB making it look like the Sahara Desert in no time at all. Thats the biggest mistake I have ever made in my 20 or so years of reef keeping, adding a sand sifting star against everyones advice, I thought I knew more than them. Not! In 3 months I had 330 lbs of dead sand and it took a year of supplementing cups of donated live sand from friends, numerous bottles of live ocean pods and many many bags of live reef stew to get it back anywhere close to where it was. To this day several years later I still don't have the spaghetti worms or pods I once had.
Good porous live rock is important. In the beginning some of my rock was dense and very heavy meaning it was not porous and would not support bacteria growth way down deep inside the rock. Bacteria grows all thrugh the rock not just on the surface.
I have no filtration on any of my systems other than protein skimmers and media reactors for carbon and GFO. No sponges, floss or filter socks of any kind and never have. They all trap detritus and produce nitrates not lower them.
20-40 is not tremendously high for a FOWLR system if you have a heavy bio load like lots of fish. I have seen fish only systems exceed a couple hundred ppm nitrates and still do well, they wouldn't support any stony corals but fish did fine.
What are you using for water, hopefully RO or RO/DI water? How often do you do water changes and do you disturb the sand when you change water? try not to disturb the sand if possible and maybe increase the frequency or amount when you do water changes.


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## new2hobby (Mar 14, 2009)

I change 10 gallons every week, week and a half. I only vacuum detrius off of the top of the sand, trying not to disturb it, but I do have four nassarius snails in there. I am using dechlorinated tap water right now, till I can get an RO/DI unit later this summer. Funds are kinda tight with two kids and college full time. I have sugar fine aragonite sand in my 55 and the next size up aragonite sand in the refugium. I cannot get south down where I live, and all of the play sand that you can buy here is packed full of silicates. So I have to pay about $1 per pound for good quality sand. Can I just layer the sand from my fuge on top of the sand in my main with out disturbing the benifical bacteria in it?


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## AZDesertRat (Apr 10, 2009)

Sounds like you are doing things right other than using tap water and you already know the pitfalls there. The EPA Maximum Contaminant Level allows nitrates up to 10 ppm in drinking water so this could be part of the problem.

Not sure where you are located but around Phoenix there seems to be a Water & Ice type store on every corner. Buying RO water would be much better than tap water and it should only run about 25 cents a gallon and often they have specials or discount days on top of that. Some use water vending machines of kiosks but I shy away from buying water from a place that is not staffed by a walking talking human. The stores by me are all more than happy to test the TDS or conductivity in my presence when I explain I am using it for a saltwater reef system and quality is important.

Adding the sands together to get a deeper sandbed would be a good idea. Since neither is real deep now you should not get a cycle or spike when doing so since there is probably little or no anaerobic activity down deep.


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