lowering nitrates and phosphates with water changes over "x" time

[noobtothereef]

My nitrates are at about 15ppm and phosphates are at about .5, yes i know its high. Heres what i want to do, my total volume is about 160 gallons, i want to start doing a 10% water change daily over the next week or so , and i am running gfo but it uses up the gfo in about a day and then needs changes, i just started running it a week ago and have used to cartridges worth in my brs gfo reactor, im thinking the water changes will aid in dropping the levels more efficiently and cheaper, a bucket of rc is $40 but gfo is alot more expensive. I also want to drop the nitrates as much as possible, i also have a koralin sulfur denitrator on order that i will be running to lower the nitrates.

[bertoni]

The water changes might be cheaper than the GFO. It's possible to regenerate GFO, too, if you don't mind working with toxic chemicals (muriatic acid and lye). The live rock might have adsorbed a lot of phosphate and could be releasing it, which would be another issue to handle. The 10% changes should be safe enough, if you're willing to do the work.

[teebs]

To reduce phosphates you might want to try lanthanum chloride but it is preferable to dose it in a 5 micron filter sock so that the precipitates will not escape into your main tank. It will be cheaper and will also reduce your PO4 levels more quickly.

For nitrates, you might want to consider dosing bacteria and/or doing regular water changes.

[TheH]

I put together a calculator for this, but it doesn't take into account any phosphate/nitrate locked-up in your live-rock.

http://www.hamzasreef.com/Contents/Calculators/EffectOfWaterChanges.php

[Nanook]

Nice calculator:thumbsup: I was looking for something like this and you shored it up nicely.

[TheH]

Thanks!