Is skimmate really that bad?

[Zizzer]

I have a 20 gallon back up tank / Qt tank that I've been dumping skimmate in for a couple months now that I get from my 75 gallon DT skimmer. I've never changed the water, only added rodi water to top it off. I tested the phosphate and Nitrate today in the backup tank. I was expecting both to be pretty high but phosphate was .06 and Nitrate was 10.6. There's no fish in it. Just copepods, sand and nuisance algae. I'm just a little confused as to how I keep throwing skimmate into a tank with no chemical filtration, just foam and ceramic tiles in a hob filter, yet the phosphate and nitrates are not very high.

 

[jda]

You are not feeding fish and introducing phosphorous, nitrogen, but also not any traces like potassium, iodine, etc.

There are biological processes in each tank that can lower no3 - anoxic bacteria. po4 will bind to equilibrium with the aragonite - the rock/sand can hold a lot and can mask a phosphate overages for quite some time

It is easy to keep waste products like no3 and po4 down when you are not feeding anything/much.

 

[MnFish1]

I have a 20 gallon back up tank / Qt tank that I've been dumping skimmate in for a couple months now that I get from my 75 gallon DT skimmer. I've never changed the water, only added rodi water to top it off. I tested the phosphate and Nitrate today in the backup tank. I was expecting both to be pretty high but phosphate was .06 and Nitrate was 10.6. There's no fish in it. Just copepods, sand and nuisance algae. I'm just a little confused as to how I keep throwing skimmate into a tank with no chemical filtration, just foam and ceramic tiles in a hob filter, yet the phosphate and nitrates are not very high.

I'm confused as to why you would do it in the first place - however, to answer your question - the algae is taking up some, and there are probably lots of unmeasured organics in the water - I would certainly not use it for a QT tank for many reasons

 

[jda]

Your skimmer likely removed some harsh metals bound to organics - a good thing. Adding those back is usually not a good idea. They are many, many functions that a skimmer performs and many, many things that it removes and only a small portion of them have to do with nitrate and phosphate.

 

[Zizzer]

Woe. Thank you. I had no idea that the sand/ araganite could absorb phosphate. That kind of blew me away after I looked it up. That really just opens up a whole bunch of more questions I want to look up. Like how fast can sand leak out the phosphate verses how fast it aborbs it.

 

[Zizzer]

I had started this experiment to see if it would help a copepod bloom. Which it seemed to have done that.

 

[jda]

Aragonite can bind and unbind quickly like a day for the material on the surface. It takes a bit longer for water to get into the sand and rock but it binds once it gets there. Think of it as pretty fluid with hourly/daily adjustments.

 

[taricha]

Also, the nuisance algae in the system is quite good at lowering testable NO3 & PO4.

 

[ReeferSamster]

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