I've just been reading through this months Aquarium World, well done to all those involved. However, the article on nitrate build up is some what misleading in that it states that without the help of plants and/or de-nitrifying bacteria it is impossible to stop nitrate levels accumulating in the aquarium with partial water changes. This isn't true.

For instance taking the example that is used in the article which assumes that the rate of build-up of nitrate is 1 ppm/day and that 20% of the water is changed weekly. After 7 days the level of nitrate would be 7 ppm and after a 20% water change on this day it would be 5.6 ppm. After another week the nitrate concentration would be 12.6 ppm and after the water change 10.1 ppm. The article infers that the nitrate concentration will increase indefintely unless 100% water changes are used, however this is not the case.

Once the nitrate concentration reaches the point where a 20% drop is equivalent to the amount of nitrate build-up that occurs in a week the nitrate concentration will stabilise. For this particular example this happens at 35 ppm. For example a 20% reduction in this value would give a nitrate concentration of 28 ppm, which after one week of build up would be back up to 35 ppm again. A 20% water change would bring this back to 28 ppm ... and so on.

Plants and de-nitrifying bacteria would just help to reduce the rate of nitrate build-up as some of the nitrate would be removed by other means than just water changes. Therefore the equilibrium nitrate concentration would be kept lower. For example it may reduce the build-up to 0.5 ppm/day, in which case the equilibruim nitrate concentration (using the same water change regime as above) would be 18 ppm.

Please write an offical letter to the editor abut this Midas and I will print it in the next issue. Or, may I just copy and paste this into it?

I print articles received in good faith. If I know something is wrong I query the writer but in this case it is not my area of expertise. Perhaps someone else agrees or disagrees with you and we could get quite a discussion going within the magazine.

Whatever, it is nice to get some feedback. The only times I have ever received letters to the editor was when I printed an article (written by Alan I might add) about breeding a banned fish and the sh*t hit the fan. Then someone disagreed with an article about making your own heatpads.

They might be complaints but it shows some people are reading it! :lol:

Hi Caryl, how do I go about getting a copy of your mag, I am in Hamilton

Hi Caryl, how do I go about getting a copy of your mag, I am in Hamilton

Here's what Caryl posted in another forum

If you join an affiliated club it is free but you can also subscribe. Costs $21.80 (p&p inc) within NZ. This is an A5 size 40 page full colour magazine produced quarterly so you get 4 magazines for the price (Feb, May, Aug and Nov).

If you wish to subscribe (joining a club is sometimes cheaper ) please PM me for the treasurer's address.

Thanks

The nitrate level will not keep on rising indefinitely. As long as there are regular water changes done it will settle out at an ultimate value.

In the case mentioned above, at 1ppm per day with weekly 20% water changes, the nitrate level will settle out at approx 30ppm after a water change rising to approx 37ppm just before the next change. It will take 20 water changes at least before this level is reached.

eg 30+7 =37, 37*0.8 = 29.6 (approx 30) and repeats from here.

Haven't read the article yet but if its incorrect or just unclear, an amendment could easily be added in the next AW. I'll even volunteer to write it!!

That would be good Warren. I don't follow anything that has numbers in it :lol:

Err, why haven't you read it yet?

The part about a DSB was interesting. I've always wondering if that would work in a freshwater tank, espeically since my cichlid tank's nitrate levels seem to bounce between high and nothing at all.

Caryl, feel free to copy what I wrote above if you want to use it.

I also have created a nitrate accumulation model in Excel that I can send through to you via email if you would like? You can enter in the initial nitrate concentration, the water change frequency and amount and the nitrate accumulation rate in ppm/day and it will provide a graph of nitrate concentration over time.

Cool, email to me and I'll add it to the technical articles section too (just like the glass calculator).

What a neat little model midas. Thanks for that. Yes, please send it to Warren.

Thanks, no worries I've sent it through.

Midas & Warren - I agree you are both correct.

IRA - A DSB does work in freshwater. I use a 10cm base in my existing tank, nitrates =0 and my freshwater is OVERSTOCKED and OVERFED. It is heavly planted. Water changes are done every 6weeks, 30%. It has no alge, water is crystal clear and health of all fish and plants is excellent. VERY HEAVY LIGHTING.

Pies

Thanks for the input guys. I will certainly make sure these additions are in the next magazine.

Oh well... i guess this is what happens when you write an article off the top of your head with limited thinking and research into it.

-- Gomer

A good learning curve I feel. Nice to know others read your article though wasn't it gomer? I for one appreciate the fact you wrote one at all!

I should of put more thought into it.

-- Gomer

Hey - don't feel bad Gomer - it's great even just to stir up a bit of conversation on the topic - having read your article and the posts here - I am finally thinking I might understand it all sometime soon! Next to experience, there is nothing as good as debate for the bystander to learn from.

I don't even try to understand it maybe that is why i'm not a reefer (and the money thing :lol: )

as long as my fish look happy and healthy and they are eating, i'm happy

Ditto to TeeCee. Enjoyed your article Gomer and more important I had glimmer of understanding...............anything technical tends to make my mind go blank.............I have totally enjoyed the discussion here too and have ended up a tad wiser. Thanks to all who contributed. IMO this is the sort of conversation that makes us better fish keepers. Looking forward to next lot of articles from ya'all.

I just wrote a small program for those who don't have excel etc. There are two versions available, one for Windows and one for Linux.

Website

Note: temporary download problems, I'll fix them after dinner.

OK, It looks like my hosting doesn't like the filetypes. I don't know how long it'll take to get the zip file for the windows version onto the mirrors, if you try and can't get it today perhaps you should try again tomorrow. I've renamed the source to a .txt file and the linux version has a .bin extension added to the end so they can be accessed.

I just found a bug in the program, I'm repairing it and reloading the new version. Typing anything other than a number causes the program to fail and it has to be force-closed.

Problem fixed, version 1.1 is up.

I can not find the Excell spreadsheet.

Thanks

I've added Midas's Nitrate Calculator to the Technical Articles Section of the site, see the link below:

http://www.fnzas.org.nz/495.0.html