Zero Nitrates, Water Changes.......Why?

[Jackson]

I asked this once on planetcatfish and was pointed towards this
http://plecoplanet.com/?page_id=829#processes_deoxy

I'm not sure if this helps lol


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[Bderick67]

Well i do believe there are minerals that build up in water. whether or not it is harmful to fish IDK. I know if you let a glass of water evaporate if the is salt or calcium in it it will be left as a solid once dry.

I asked this once on planetcatfish and was pointed towards this
http://plecoplanet.com/?page_id=829#processes_deoxy

I'm not sure if this helps lol

Thanks, looks very informative, I only scanned over it. It will be an interesting read later on.

 

[duanes]

This is a protein skimmer working on fresh water.

Skimmers work easier in salt water, because it is more dense, but with a little more agitation than most fresh water aquarists attempt to use, it is a powerful tool, as you can see above.
I generally have a nitrate residual of 2-5ppm using fractionation, and planted sump/refugiums, and frequent partial water changes.
I believe this is because fractionation removes many nitrate precursors, and once removed, foam subsides until those build up again.

 

[pk705]

I've never seen any study finding a growth hormone inhibitor or any other regulating hormones in water. (These hormones do exist, e.g., I think tadpoles have them, but I've never seen it found with fish.) I'm not saying they don't exist, but I'd think if it were there, it'd be a cinch to find it, and I've failed at finding those studies. What I have found is that the most important factor impacting growth is food, with degraded water conditions and stress as distant seconds or thirds on that list.

I'd also question the idea that minerals do not dissipate in tank water. 1) again, I can find no studies where anaylsis compared clean to "used" water regarding all the minerals in the water. 2) Fish consume minerals and use them. While one can say they haven't "gone" since they are in the fish's tissue, the water loses what was there. Unless food provides a replacement for what was used, the pertinent minerals and vitamins are no longer available.

Fish that are crowded or inhibited by a threatening fish are stressed. Stressed fish eat less and stressed fish have reduced regulatory systems. If they grow slower it's likely due to reduced food intake, reduced 'natural' hormones that enhance growth or inhibitory effects from missing minerals/vitamins or increased levels of nitrate.

I haven't found any studies to support the hormone in water theory, either. All my replies are based on the assumption that we're super paranoid of any hormones that might potentially maybe exist. I agree on the mineral part; however, many south american fish live in water that has a very low concentration of minerals (compared to tap) anyway. edit: minerals probably accumulate in water with top ups (assuming you're not using RO/DI for top ups). This is probably not detrimental until you reach the point where your water is extremely "hard" as opposed to natural conditions. Might take a few years to get there though.

When we talk about stress, I'd like to point out that, in humans at least, when stressed, cortisol is released. It's a hormone that among it's other functions, promotes the breakdown of protein. So, a contributing factor would be stress hormones preventing growth as well. In this perspective, over crowding could be as big a problem as bad water conditions.

As for redox - it's a measure of water's potential to reduce/oxidize molecules. I believe most ozone and redox are explained here better than I ever could:
http://reefkeeping.com/issues/2006-03/rhf/index.php
http://reefkeeping.com/issues/2006-04/rhf/index.php
Short summary for those who don't want to read: basically, in water, oxidation and reduction reactions happen all the time. A high redox potential would mean that the water has a relatively high potential to oxidize as opposed to reduce molecules. (ammonia is oxidized to nitrate, nitrate is reduced to ammonia). There are two principal ways to raise redox - add oxidizing agents (such as ozone) that oxidize solids or remove solids before they can be oxidized (which is what purigen most likely does and what protein skimming does). It's a very abstract measure and is only really usable in a few specialty applications, such as bacteria denitrators and ozone reactors.

 

[Bderick67]

This is a protein skimmer working on fresh water.

Nice

As for redox - it's a measure of water's potential to reduce/oxidize molecules. I believe most ozone and redox are explained here better than I ever could:
http://reefkeeping.com/issues/2006-03/rhf/index.php
http://reefkeeping.com/issues/2006-04/rhf/index.php
Short summary for those who don't want to read: basically, in water, oxidation and reduction reactions happen all the time. A high redox potential would mean that the water has a relatively high potential to oxidize as opposed to reduce molecules. (ammonia is oxidized to nitrate, nitrate is reduced to ammonia). There are two principal ways to raise redox - add oxidizing agents (such as ozone) that oxidize solids or remove solids before they can be oxidized (which is what purigen most likely does and what protein skimming does). It's a very abstract measure and is only really usable in a few specialty applications, such as bacteria denitrators and ozone reactors.

Thanks, I'll have a read

 

[Oughtsix]

I have a sump, a big DE filter and at least a Dozen Pothos each over 6 foot long (They all started about 6 inches long). Nitrates are always under 10ppm. I do big water changes only every 3 months.

The only detrimental effects I can see is the Pothos leaves noticeably yellowing instead of being their a deep green. I figured this was probably related to iron levels in the water... although I top off the tank at least once a week.

 

[houie925]

Haven't done a WC in this guy since my last move, almost two years ago. Always zero ammonia, nitrite, nitrate. 10g with Guppies, MTS, and a fan shrimp. loads of plants and light stock seems to work in this case.


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[David R]

Interesting thread and something I've been pondering lately, given that I'm setting up a 2000 litre tank and I'm reliant on catching rain water on my roof to fill it up (not to mention drink, shower, cook etc!), I certainly don't want to be wasting more water than I need to.

Minerals do not evaporate, they will build up over time with small water changes or just topping off. What will this do to the health of the fish, the overall health of the system? This is the knowledge I seek.

My 2c... We know about Nitrate, Nitrite and Ammonia, we measure the TDS and Conductivity, but is that all there is to it? I highly doubt it. Even with my low TDS (<10ppm) tap water preventing a build-up of minerals from evaporation I would be reluctant to give up water changes altogether even if my parameters were ok. It simply isn't natural, unless you're keeping killifish that live in tiny puddles, and with the long-term effects of the unknown factors being basically immeasurable it's not worth me experimenting with my precious fish that come from riverine environments where they receive a constant waterchanges. On the other hand, I've long wondered about this religion of compulsory massive water changes and just how much time/water/electricity it wastes. My conclusion (based on not much scientific, just a lot of pondering) is that the best compromise is to try to reduce the amount of water that needs to be changed by feeding moderately and running pothos, but still maintaining a modest wc regime to counter the unknowns.

Its nice to have redundancy, if you can go a month without a WC and your measurable parameters are all in check then thats fantastic. Is that a reason to completely give up on water changes until any adverse effects become apparent? Not to me it isn't. Sorry I can't offer anything more solid than that, but I'll be watching this thread with interest!

 

[Bderick67]

Yeah, don't think I'll ever get rid of WCs, especially in the summer when I gotta water the flowers and lawn anyways. Why not use the tank water for that and replace with fresh water.

 

[gangster]

Im really diggn this thread. Id really like to see how this works w/ monster fish. Brian I know you have some very large aros. How long are you going in between wc's? ANd are you noticing a difference in your fishes behavior w/ the fewer wc's and pothos? Compared to no pothos and more wc's. Alsol...lets see some more pics of how you guys have your pothos set up. Id love to have some cool flowering plants in my over flow box....and maybe some watter lettuce or something in my main tank on the surface to help w/ filtration.