Will Purigen reduce needed frequency of water changes?

Nutrients, fertilization, substrates etc
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Jim P
Posts: 8
Joined: Sun Jan 15, 2017 4:33 pm
Real Name: Jim P

Will Purigen reduce needed frequency of water changes?

Post by Jim P »

Hi,

QUESTION (freshwater): fish wastes generate ammonia, and beneficial bacteria convert that to NO3, then nitrate. If plants consume (wild guess) 5% of the NO2, I need water changes to dilute/remove the remaining 95%.

If PURIGEN adsorbs (and/or absorbs) 90% (again guessing) of the fish wastes, then I should have around 90% less nitrates, and the plants should consume more like 50% of the nitrates, which should greatly reduce need for water changes to reduce nitrates – right?

And there could conceivably be a balance of bio-load (quantity of fish) with quantity of plants, lighting etc that would generate low/safe nitrate levels?? [I realize there are other water accumulations and depletions that necessitate water changes (anyone have a link to good tech info on those – or my NO2 question?)] Thanks Jim P
JLW
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Joined: Sat Oct 22, 2011 7:56 pm
Real Name: Joshua / Batfish
Location: Silver Spring

Re: Will Purigen reduce needed frequency of water changes?

Post by JLW »

Hey Jim,

You hit the nail on the head with the last part of your sentence. In theory, you could run all sorts of nitrate absorption media. You could even use a denitrifier -- I use them on some reef tanks. The trouble is that nitrate is the least of your worries. Not only is there nitrate, but there's all the OTHER components of fish waste -- phosphate being the one we worry about most. There's the accumulation of salts in the water from constant top-offs, and the accumulation of various proteins and complex organics that aren't readily broken down, including pheromones.

While we think of pheromones being the "romantic" protein, they do a lot of other stuff, too, including reducing fish growth. There's been lots of studies done that show that the groups of fish kept in the same water chemistry and with the same levels of nitrogen in the water grow slower when cramped, are less healthy, and more prone to deformities (most of the studies done on fry). That is, it's not just a result of nitrate in the system, it's a result of these pheromones.

Plus, there's the build up of chemicals released by the plants, ranging from alleopathic compounds to stuff like tannic acid and other complex phenol compounds.

Nah, you gotta get all that stuff out of there with regular water changes. No way around it, sorry!! :)
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