How do you lower phosphates when nitrates are 0?

[joelespinoza]

I am curious how everyone here lowers phosphates when their nitrates reach zero. Do you use GFO or add nitrates to the tank somehow? Possibly drip a small amount of ammonia into the sump? I am looking for a cheap way to get P down a bit.

I am still not 100% sure my problem is P, but I never have nitrates and my DT grows quite a bit of brownish looking algae on the glass, I am starting to get some bubble algae sprouting up on the rocks, and my coraline growth is minimal even though my alk/cal/mag numbers look great. It is possible that either my scrubber is not powerful enough (quite possible and have upgrades on the way) or that I have some phosphate in my water.

Anyway, if there is a cheap method to lower phosphates a bit I figure it would be cheaper to try that then to buy a test kit for them. What do you guys think of putting a few drops of ammonia into the sump?

[kerry]

You really need to know if your phos is elevated. No since in experimenting on your tank if there is no need to. API has a cheap Phos kit. It might not be the most accurate kit but at least you would have an idea. I would say NO to the ammonia!!!

[joelespinoza]

Here are some pics of what I am dealing with, I scrubbed the front glass completely clean 6 days ago:

Front of the glass:


Through algae covered glass to rocks with almost 0 coraline growth:










Bubble algae:



Full tank:

[SantaMonica]

Nitrate is never zero. If you want to prove that to yourself, get a low-range N kit, not the high-range one that everyone uses. It it were zero, you would not have algae in the tank.

Every bit of food, pee (especially) and poop that goes into the water adds N.

You don't need to add anything to make it happen.

[Floyd R Turbo]

Here's where I'm going to disagree because for a very long time I have tested rock-bottom zero N on Salifert looking through the side and still have P. With that much live rock, you will have a decent amount of naturally occuring denitrification occurring that will cause N to bottom out and the scrubber will stop taking up the excess P. I have encountered this personally as have many others on this forum. The additional denitrification mechanism without an additional phosphate removal mechanism means your P will rise.

Adding a very small amount of GFO in a decent flow location will help keep P in check, as long as you don't use too much to the point where it's pulling all of it out completely and then limiting P causing N to rise.

As far as P test kits go, IMO they're all worthless when you look at the visible kits (API, Salifert, etc) because the range just gets too low to give you any useful information. Get the Hanna Phosphate Checker and make sure to order extra reagent packs, and follow the instructions properly.

[joelespinoza]

With that much live rock, you will have a decent amount of naturally occuring denitrification occurring that will cause N to bottom out and the scrubber will stop taking up the excess P. I have encountered this personally as have many others on this forum. The additional denitrification mechanism without an additional phosphate removal mechanism means your P will rise.

Yea, I think this might be what I am experiencing.

As far as P test kits go, IMO they're all worthless when you look at the visible kits (API, Salifert, etc) because the range just gets too low to give you any useful information. Get the Hanna Phosphate Checker and make sure to order extra reagent packs, and follow the instructions properly.

Yea, I am a bit unwilling to spend money on a questionable test kit, and I dont have the budget for the Hanna one, I think it would be easier to experimentally lower P by a small amount and observe the results.

You really need to know if your phos is elevated. No since in experimenting on your tank if there is no need to. API has a cheap Phos kit. It might not be the most accurate kit but at least you would have an idea. I would say NO to the ammonia!!!

That kit apparently would not tell me anything, and out of curiosity, why are you so opposed to adding a SMALL (a couple drops at most in a day) amount of ammonia to the sump? I would rather add pure nitrate, but its not as easy to come by. I guess I could add CO(NH2)2, which would probably be less toxic and it is easy to come by =).

[Floyd R Turbo]

http://www.aquariumfertilizer.com/in...ditU=2&Regit=3

[kerry]

Ammonia is way to deadly, I vote for Floyds link for the fert.

[SantaMonica]

If you want to add anything to the water, just add food.

[joelespinoza]

If you want to add anything to the water, just add food.

But wont food add phosphates and nitrates?