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Right on, Dennis,

My web page calcs say .3 ml per 10 gallons to get 1 ppm. You probably have 7 or 8 gallons in the tank so its about perfect. That is, as long as you are measuring out .25 ml and not using the drops. The syringe method you use sounds good!
see:
http://users.ev1.net/~spituch/Chemicals/chemicals.html#Phosphate from Fleet Enema

How many hundeds of dollars did you spend on the P kit? :lol:

Try to get a baseline on the P you just added. If it doesn't correlate, don't use it.

Regards,
Steve Pituch
 

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Hi Dennis,

I had a Hagen test kit that went bad because the last reagent was in a plastic bottle. They sent me a new (glass) bottle, but distilled water reads like 1 ppm. I know someone who only uses the Hagen kit as a ball-park estimate: either no P or enough P, but no trying to figure out an exact amount. If its not a Hach or Lamotte test kit, I wouldn't bother. I think 1 ppm P twice per week is quite a bit. If you were starving the plants of P within a week they should catch up. With 50% weekly water changes the max possible would be 4 ppm if the plants stopped using it. I would either dose 1 or 2 ppm twice per week and forget about the test kit and spend the time enjoying the aquarium.

There is a decent amount of P in fish food. The way people are into fish on the APC here, (normal planted aquaria people aren't) there should be a lot of P in the substrate. Walstad says virtually all the P in fish food goes to the plants assuming your fish are fully grown. She also says that sediments sequester P. They are like a P magnet. One pond had P in the water column of .04 ppm, while the soil had it at 1000 ppm. Thats a 25,000 to 1 ratio. I don't know how your substrate compares to a soil substrate as far as binding P goes, but it could be all going into the substrate. That means it is available to plants. This is one of the good reasons to have Walstad's book. It makes one really think about what is going on in the aquarium. I think its required reading. I read it about ten times to understand it, and still refer to it.

So, forget about the test kit, and start enjoying the tank.

Steve Pituch
 
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