# How to handle chlorine in my DIY auto water change?



## Edward Shave (19 Jan 2021)

I am experimenting with a DIY drip auto water change system.
Currently I am not adding any kind of de-chlorinator just dripping tap water straight into the tanks. So for example my 200L gets about 4L of fresh (tap water) per hour (96L per day) and the same amount is removed via a kind of self regulating siphon. The tank holds 200L of air when empty so a lot less water allowing for the space above the surface and displacement by way of contents. However I use the 200L figure as a rule of thumb when making calculations here as any errors are on the safe side.

Using an online calculator I estimate the tank is getting the equivalent of a 40% water change every 24 hours.
My water company tells me the average measured level of chlorine over the past 12 months was 0.29 mg/L. The highest reading was 0.63 mg/L. That's not to say those readings were the same as my personal tap water which should if anything be lower by the time it comes out of my tap. My water company does not add Chloramines .

The only means I have to measure chlorine is the Tetra 6 in 1 test strips. I understand these strips cannot be relied upon for accurate measures but I assume they will at least indicate the presence of chlorine. In my case I can see no discernible colour change when dipped in my tank. To be sure I tested some distilled water and got the same result. There was a barely perceptible colour change when testing my tap water but still less than 0.8mg/L if the colour chart is to be believed.

The tank has reasonable water flow and a spray bar running end to end powered by 2 x 800LPH external filters. So I have been working on the assumption (rightly or wrongly) that the chlorine will begin to evaporate as it's introduced and reach equilibrium at a very low (safe) level.  However even if that's right I still would like to do something about chlorine in the long run in case there were to be a sudden short term increase. So I have been thinking about dosing Prime/Safe via a peristaltic pump or using an inline carbon filter.

Prime/Safe
Problem with these is how to dose very small quantities. In the case of Safe I would need to dose around 2 mg/hour and for Prime 0.1 ml/hour. Any ideas?

Carbon Filter
I'm a bit unsure of what is fact and what is fiction when reading about carbon filters. My current thinking is that activated carbon may take stuff out that my fishes and plants currently use. I don't add any fertilizer other than root tabs. So since I'm only interested in removing chlorine, would non activated carbon be a better bet? And if so where to get it as I can only see activated carbon on offer when googling. Also due to the relatively slow flow through the carbon I'm thinking I can use a cheap inline filter housing for the job such as this... Refillable InLine Filter Housing for DI Resin / Carbon Any drawbacks going this route?


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## Hufsa (20 Jan 2021)

Would it maybe be possible to dilute Prime using distilled water, making it a suitable volume to dose with a doser? As far as I understand it is more accurate to dose 10 ml of something rather than 1 ml, even if it contains the same in mg/l / ppm.

Also paging @Wookii , who I seem to remember has a lot of automation.


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## Edward Shave (20 Jan 2021)

Wow didn't expect such a quick reply this time of night  Thankyou.
I did think of this but having read and old post in another forum by a Seachem employee saying not to dilute Prime as it may spoil over time I went off the idea. I did get the impression however that it would be fine up to 24 hours or so. I think if I could stretch that to 48 hours it could work for me... Any experts out there?


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## Hufsa (20 Jan 2021)

I read this article, where the author claims to have tested making making Safe into a solution.
I am a little bit dubious about some of the articles the author has made on his site, but some of them are pretty good and generally liked by the community. 
I think most everyone agrees that dechlorinators deactivate potassium permanganate, seeing as it is used to stop PP after using it as a treatment. 
So you could do the test yourself if you wanted to. I would be really interested to hear the results, as I have both Safe and Prime but have not started to use Safe yet because Prime is easier to dose.


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## Edward Shave (20 Jan 2021)

That's really interesting and would certainly solve my problem if true. Will be interested to hear what others think...


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## Wookii (20 Jan 2021)

Hufsa said:


> Would it maybe be possible to dilute Prime using distilled water, making it a suitable volume to dose with a doser? As far as I understand it is more accurate to dose 10 ml of something rather than 1 ml, even if it contains the same in mg/l / ppm.
> 
> Also paging @Wookii , who I seem to remember has a lot of automation.



I did actually contact Seachem some time ago about making a solution of Prime with DI water for use with my autodoser, and it was basically a no-go. They said that the Prime solution contains various stabilisers that ensure the product has a good shelf life, and if those stabilisers were diluted, they couldn't guarantee that the effectiveness of the product wouldn't deteriorate over time.

For me that was too much of a risk with something as essential as a dechlorinator. In the end I simply had to find an off the shelf dechlorinator that would result in sufficiently high dose volume to work with the auto-doser. I therefore buy 2.5 litre containers of API stress coat, which last me around a year with daily 25% automated water changes.



Edward Shave said:


> I am experimenting with a DIY drip auto water change system.
> Currently I am not adding any kind of de-chlorinator just dripping tap water straight into the tanks. So for example my 200L gets about 4L of fresh (tap water) per hour (96L per day) and the same amount is removed via a kind of self regulating siphon. The tank holds 200L of air when empty so a lot less water allowing for the space above the surface and displacement by way of contents. However I use the 200L figure as a rule of thumb when making calculations here as any errors are on the safe side.
> 
> Using an online calculator I estimate the tank is getting the equivalent of a 40% water change every 24 hours.
> ...



I know some people on this forum do water changes without dechlorinating the water, and report no issues, but I personally think you are taking a bit of a risk there Edward to be honest, particularly with such a high water change regime.

You may be right that the current levels of Chlorine are off-gasing on their own, but the water company could increase the amounts at any point, or worse they could decide to add Chloramine also which won't off-gas (particularly with all this flooding we are now having). Also bear in mind that with 40% daily water changes, there may always be a certain level of chlorine in the tank which could have a long term affect on your livestock.

The last point you make is, I think, the solution to your needs, but not refillable units for granular carbon - you need to look at inline HMA filters that use carbon block filters. Devotedly discus do a range, but many 'water filter' companies have models available too:






						Tap Water Filters
					






					www.devotedly-discus.co.uk
				












						10" 3-Stage Pond Dechlorinator HMA Heavy Metal Removal
					

10 inch HMA 3-Stage Pond Dechlorinator consisting of three standard 10" filter housings to meet all customer's fixed-capacity filtration needs.




					www.vyair.com
				




In both cases I could recommend including a chloramine filter cartridge. At you slow flow rate you should ensure 100% removal of both chlorine and chloramine (and heavy metals). You would then just need to change out the carbon block filters every 6-12 months. I intend to add one to my low tech tank at some point as a better solution than my current dechlorinator dosing.

I'm unsure on whether the carbon block filters will remove any essential elements from the water supply (specifically micro-elements such as iron and zinc etc). I don't believe they will affect macro salt levels, so nitrate, phosphate and potassium in your water supply should be maintained through to the tank. All that being said, if you want healthy plant growth in your tank, I would recommend at least some level of water column fertilisation. You could easily add a mirco fert once or twice a week to compensate, or dose it daily if you already have an auto-doser - micro solutions are easy and cheap to make up DIY.


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## ian_m (20 Jan 2021)

As pointed out you can get "DeChlor" water filter cartridges that specifically will remove chlorine and chloramine. I think the trade name is "ChlorPlus". Used in conjunction with a pre-filter.

Biggest issue with these is they fail to work if flow rate is too high and must be replaced promptly once "worn out". The issue of when worn out is hard, as you either test your outgoing water for chlorine or have an accurate flow rate meter to determine when sufficient water has passed through and also assume you know incoming chlorine/chloramine levels. Also when worn out and with chloramine in water, they tend to split it to chlorine and ammonia, where the ammonia is many many times more toxic to fish than the chlorine. Search for Rory's fish house where the chloramine and poor filtering wiped out £600 worth of fish.

Also why are you doing such a large volume of water change per day ?

Any plant fertilisers you dose, a large amount will be wasted, taken away in your waste water ?

What about automatically storing tap water in a container, peristaltic pump dosing prime, leave for a while, then pump to the tank, say only once a week ? That guarantees the 100% sorting of the chlorine/chloramine levels. This is extremely common in the salt water world as a way of water changing.


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## Wookii (20 Jan 2021)

ian_m said:


> What about automatically storing tap water in a container, peristaltic pump dosing prime, leave for a while, then pump to the tank, say only once a week ? That guarantees the 100% sorting of the chlorine/chloramine levels. This is extremely common in the salt water world as a way of water changing.



I probably should have mentioned above that is what I do currently on my low tech tank - I dose the dechlorinator into a container (a header tank on the wall next to the tank), fill the container with water (automatically using solenoids on the incoming water supply), mix for an hour with an airstone, then release the mixed water to the tank (via gravity and another solenoid) - waste water being displaced over an overflow.

On my high tech which uses RO, I also fill a floor level tank, and then use a peristaltic pump to add to the tank as Ian suggests above.


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## Edward Shave (20 Jan 2021)

Thanks for all the input...

My current thinking is that it's probably safe to dilute Safe or Prime so long as it's used within 48 hours. It maybe it's okay to store it indefinitely but I don't feel so confident on this. However 48 hours is enough to make dosing via peristaltic pump a practical proposition.

I haven't had any adverse comments regarding using activated carbon in a planted tank (yet..!) and this would be my preferred option as it's less complicated than the peristaltic  pump idea. So I think that's what I will do.

In the absence of any further input let me say thanks again to all respondents.

Ed


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## dw1305 (20 Jan 2021)

Hi all, 


Edward Shave said:


> Currently I am not adding any kind of de-chlorinator just dripping tap water straight into the tanks.





Wookii said:


> I know some people on this forum do water changes without dechlorinating the water, and report no issues, but I personally think you are taking a bit of a risk there Edward to be honest,


My guess would be that the method of water change means that the risk from chlorine is relatively small. You are going to have drops with a large surface area to volume ratio, meaning that steep concentration gradient between drop and air (atmospheric Cl2 reads in parts per trillion) will outgas the chlorine pretty effectively.   Having said that I would be *really concerned about emergency chloramine dosing. *

I've read a couple of <"chloramine horror stories recently"> and that is a large volume of water entering the tank. 

cheers Darrel


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## Edward Shave (20 Jan 2021)

dw1305 said:


> *really concerned about emergency chloramine dosing.*


Thanks Darrel, Yes I am concerned that I can't rely on the chlorine being supplied always remaining at current low levels.  So if only for peace of mind I am going to install an inline carbon filter. Currently have my eye on... Amazon product.


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