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W/C's ... the forgotten do-it-your-self-project

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This thread seems to have been put to rest as the consensus seems to be with the big water changes.  I am 100% on board with this but I do have a question about the fresh water being used. I'm on the south side of Calgary, I run 2x75g and 1x180g tanks on a single sump with a 60g capacity,  I over filter like crazy and do my weekly 25-50% water changes time dependent. I have been treating my replacement water with Prime for years usually panicking when I run out but recently I did run out adding straight tap water for a few weeks in a row without seeing any negative effects. I keep primarily Malawi Cichlids (all types) with a couple of Synodontis Njassae and a couple of common plecos.

I must confess that I did pick up another bottle of Prime but my question is this; Is it necessary to treat Calgary Tap water before adding it to the tank. ?

I'd also like to add a curiosity question; If I am changing approximately 200g per week would it be as effective to do 30 gallons per day? At this rate my RO system can easily be used to do the water changes but my  system can't produce enough water fast enough for the big changes not to mention I have used all of the space I am allowed by my lovely wife for tanks so there is no room to have a holding tank for the RO to produce into to be used for the water changes.

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If you are keeping Malawi cichlids and other fish that need, like, or at least tolerate hard water then there is no incentive to use RO water apart from getting rid of the chloramine. But prime is a lot easier and probably cheaper. Untreated Edmonton water kills hydra very effectively, which was enough to make me believe it would not be beneficial for fish either.

Seven 30 gallon changes will be slightly less effective than 1 210 gallon change per week. It will be more gentle in causing smaller swings in water parameters but you are disturbing the tank more often. The latter may be less of an impact if you add the water to the sump. Either way I don't expect there to be much difference for the fish but for one a week would be easier on time management.

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I am currently running 24 gal per day drip into a ~280 gal system, and I pass it through 2 x carbon blocks. I think it's time to change the carbon blocks after 4 months, as I'm noticing some behavioral changes - I'll probably change the 1st one now and the 2nd one in a couple months. That way I'll get 4 months per block and always have a new one every 2 months.

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Hey Fishman44 I have a couple of comments for you. Firstly, if your doing water changes in tanks that keep Rift Lake Cichlids (I’m looking at the Haplochromine in your picture), our water from the Glenmore reservoir is beautifully suited for their needs (Chlorine excluded). I do 80-90% water changes every two weeks, and anecdotally my fish are thriving. This result would be expected because they have evolved for millennia in very similar water chemistry, so I would say ditch the RO system if you have African Cichlid specific tanks (gradually of course). As for Prime. Thats an interesting question because the city ideally wants to give everyone the same residual chlorine concentration when the water hits your house, but there are so many variables that prevent that from happening. For example, in the spring during runoff their system is taxed and our free chlorine levels can easily double (0.7 to 1.4 mg/L). So, prescribing a dechlorination free methodology may be tolerable for your fish at certain times, it could easily be toxic at other times. I would recommend to my friends that they use Prime, especially if they do really large periodic water changes like me. If your doing the more frequent but smaller volume regime, it may very well not need any Prime because those Chlorines flash off before anything detrimental happens.

Your curiosity question sounds like a math/calculus problem in which I have no skill or desire to tackle.

HTH

Andrew

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I'll take on the 'trivia' question and do so without any formulas.

Assume your tank inhabitants produce enough nitrate during one week to raise nitrate levels from 0 to 20 mg/L. And you consider to do one tank volume water replacement per week but have to decide between one 100% replacement or two 50% replacements.
- in the weekly case the replacement happens at the end of the week when nitrate concentration is 20 mg/L, and when the replacement is done you are back to 0 mg/L. The average concentration over the week is 10 mg/L but with big swings during the week.

- in the biweekly case the first 50% replacement happens midweek when nitrate levels have accumulated to 10 mg/L, that drops the level to 5 mg/L. The next half of the week adds another 10 mg/L so you end the week with 15 mg/L when you do the second 50% replacement. You end up with 7.5 mg/L of nitrate at the end of the week compared to 0 mg/L in the first case.

The reason for the difference is that the amount of nitrate you remove per week must be the same as what is produced and the amount removed depends on volume and concentration. In the first case you let concentration grow all the way to 20 mg/L so you remove a lot of nitrates. In the second you do the replacements at much lower concentration so you remove less. Over many weeks the nitrate concentration in the biweekly schedule will keep creeping up until the average is 20 mg/L in which case you remove the same amount as the weekly schedule. If you were to do more changes per week but kept the total weekly amount at one tank volume you would also end up with an average nitrate concentration of 20 mg/L but you'll get there faster and it will vary less around the 20 mg/L average.

So more frequent changes give smaller swings in nitrate concentration but a higher average nitrate concentration. Now if you add a good dose of (floating) plants they will easily take up 20 mg/L worth of nitrate per week so you need virtually no water changes, just top-ups, and your weekly average nitrate concentration is near-zero as ammonia produced by the fish is taken up immediately. Perhaps not an option with rift lake cichlids, just a thought.

For more on plant-based aquarium filtration see: http://biodives.com/blog/?p=6 

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Wow, extra glad I got this thread going again.  I have been in the hobby for many years and have shared a dream with many others, the maintenance free aquarium.  I know there will always be a need for some maintenance but with three teen aged kids all active in some thing or another any time I have to enjoy my hobby is often involves maintaining it.

Biodives,  I do appreciate the detailed comparison of the effectiveness of large weekly vs smaller daily water changes.  I also enjoyed reading your blog on the planted filter system, I had a plan in place for something quite similar when I was designing my current setup but the Africans won again.  I always go back.  I do have a space in my sump that could easily be set up as a refergium,  I would be interested in some suggestions for the best filter plants if appearance is not really a factor but high water flow is. 

Jvision,  I'm thinking that the flow through design might work out for my particular setup.  I am fortunate to have full access to whatever plumbing I wish to install and with my tank built into the wall I can hide it all. I think I may even be able to just bypass the RO cartridge of my existing filter system.

Funksolid, until I can confirm that the water I am introducing has no chlorine in it to harm my fish I think at the cost of prime vs dead fish, I'll go with the prime.

Edited by Fishman44
typo

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