Automated Water Change/Chlorine

[cich_mind]

I'm setting up a 90 gallon tank where I would like to plumb in automatic water changes. The local water supply engineer assured me that only free chlorine is added to the water (not chloramine). The water quality report says the average concentration is 0.7ppm, ranging 0.2 to 1.1 ppm. Interestingly, water hardness is stated as 63ppm with a high variance.

To deal with the chlorine in an automated way, I'm seeing several options:

1. keep a reserve tank with floats and pumps and so forth so that water can collect and off-gas the chlorine. A one-time investment but multiple failure points and a clutter.

2. Install an RO unit which has a reserve tank anyhow. So I'm not seeing this as a better alternative. And these filters seem to require prefilters anyhow including activated carbon, so this method seems overly expensive and duplicates other methods. Also the flow rate is reduced, if I understand correctly. That's a lot of effort and expense (including periodic replenishment of prefilters) just to remove chlorine. It also softens the water, not sure I care about that.

3. Install a conventional inline under-sink activated carbon filter. The performance data sheets on these suggest that they treat 1000 gallons or so. Weekly changes of 50 gallons would suggest that a cartridge would be spent after 20 weekly water changes, or about 5-6 months. Same math if 50% water change is spread out over a week. New charcoal cartridges are $30-$90, who knows what explains the variance.

4. Use an automatic doser to add dechlorinator just after the automated water change completes. This involves an initial investment similar to above options but a monthly expense to purchase the dechlorinator. This method has the advantage of removing chloramine just in case the water supply changes methods without telling us. The API tap water dechlorinator treats nearly 4800 gallons, for about $14. So a 50% water change (45 gallons) per week would last nearly two years. This seems like the most elegant and cost-effective solution. One issue is that we would need to be sure that the dechlorinator is not one which requires shaking of the bottle.

5. Do nothing. By changing out 10% of the water, the chlorine level in the tank would be 1/10 of the tap water or about 0.1ppm. The question is how fast would this off-gas? Would it slowly accumulate with each daily water change? In a 78-degree tank, wouldn't the chlorine be gone by the next day?

Am I thinking about these options clearly? I'm leaning toward option 5; if monitoring shows accumulation of chlorine I can add the autodose of dechlorinator.

 

[TetraFreak]

I have a Rain Soft whole house filtration system.

It takes all the bad crap out of the water and softens it up.
pH about 7
GH 1
KH 3
and I'm awaiting the delivery of a TDS meter to verify that.

I take water directly from the tap to go into tank without adding anything. The fish love it and the water is exceptionally clear as well!

 

[TwoTankAmin]

This may help:

Karl Lembke
Supervisor, Water Quality Inspectors, Los Angeles Department of Water and Power
Answered 3 years ago · Author has 179 answers and 376.1K answer views

Chlorine gas used as a disinfectant in water is in solution. It is easily dissolved in water, and will escape from the water, as easily. If there were chlorine in the atmosphere, the concentration of the gas in water would reach an equilibrium where chlorine in the air is dissolving into the water as fast as chlorine in the water is escaping into the air. Since there’s basically no chlorine in the air, the equilibrium point is zero.

Chloramine takes a lot longer to escape from water. While chlorine gas will escape with a half time measured in hours (depending on the shape of the container, and therefore how large a surface is in contact with the air), chloramine escapes with a half time measured in days.

Other chemicals that will dissolve in, and escape from, water include pretty much any atmospheric gases, and the set of contaminants known as volatile organic carbon (VOC). Oxygen reaches a decently high equilibrium value in water, which is a good thing for fish. The fact that VOCs escape from water given sufficient exposure to air makes it possible to remove these chemicals from water by various forms of air-stripping.

from https://www.quora.com/How-is-chlori...at-other-elements-are-released-from-tap-water

Bear in mind that the above is for standing water. When the surface is being agitated as in most tanks, there rates if faster. So, the issue of most importance for you relates to what your water company is doing. Switching to chloaramine, as you noted, is one risk if you are not made aware of this well in advance of it happening.

But there is a second danger which is when a water company has an issue for which the solution is to do a short term increase in the amount of chlorine. I believe this is something they are supposed to announce, but we have a private well so I am not sure of this.

You did not indicate the sort of automatic changing system you want to use. If it is a drip overflow system and the tank has decent surface agitation, then I think you are OK with option 5. You could protect yourself further with a small autodoser for liquids. Just fill it with homemade dechlor (for ex: SeaChem Safe)
https://seachem.com/safe.php

@ T TetraFreak
You are in for a surprise. TDS measures everything, GH does not. Salt is a perfect example. But TDS will count ions such as nitrate etc.

 

[cich_mind]

Regarding the water company, in my experience any public disclosure of their changes are posted on their website, but who on earth reads the local utility websites on a frequent basis?

Your link to the Quora site is encouraging. I wonder where this kind of thing is actually documented.

Water changes. I'm afraid I hadn't gotten that far. I was envisioning a valve which mixed cold/hot water to a reasonable temp, then have a solenoid on timer to release water into the tank for so many minutes, then a surface skimmer connected to a drain, but I haven't had much luck finding a decent tutorial on how exactly to do this in a reliable way. Any suggested links?

I'm going this whole route because I used to keep an aquarium and the water changes started to become tedious. Realistically speaking I will procrastinate on them, and I hate slugging buckets around, inevitably getting the floors wet, etc. So I'd rather pay the money and effort to automate this so that I'm not tempted to put off maintenance.

 

[dudley]

C cich_mind , if you will only have the 1 tank, consider getting a Python water changer or you can go the cheaper route with a water bed drain/fill kit (sans the conditioner) and a 25 or 50 foot drinking water safe hose. The only other thing to be sure is that the faucet you want to use will have threads, usually found once you remove the aerator.

 

[fishorama]

I think would go with a doser. Even if your water co. "purges" the system with extra chlorine (& they do, often seasonally) you should be OK. I believe if they switch from chlorine to chloramines they'd have to tell you in advance but that may have been in the "olden days" in a different state. But a dechlor like Prime (liquid) or Safe (dry) treats both.

I've always wanted an automated WC system but my tanks are all over the house. Since I don't have a basement or a good way to set that up, I would do like dudley suggests. You can drain to a floor drain, bathtub or outdoors. My east coast discus buds had a U shaped PVC connected to a hose & shut off valve to a drain. & another connected to a refill line. You do need to pay attention to both draining & refilling for this manual style, temp can be an issue too.