R.O. and water changes

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Keith Wolcott
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R.O. and water changes

Post by Keith Wolcott » Sun Mar 04, 2007 8:15 pm

I am going to use R.O. water for all water changes in order to get soft water since the local water here is very hard. I'm looking for information on the best way to make this work efficiently and to be at least partially automated.

I am considering having a sump and a separate storage tank of the same size. The storage tank would be filled from the R.O. filter and be heated and aerated. Before a water change I would add the necessary minerals to the storage tank that have been removed by the R.O. filter. The sump would have a drain that could be opened and emptied of 90% of its water, but without turning off its pump to the aquarium. Then the prepared water in the storage tank can be pumped into the sump.

It should be possible to have this somewhat automated.

1. Put a float controlling a valve on the input for the storage tank to keep it full.

2. Put a float on the sump to turn off the pump from the storage tank when the sump is full.

3. Put a float (a reverse float?) at the 10% level of the sump to automatically close the drain valve and start the pump from the storage tank.

Then the only thing that must be done manually is to add minerals to the water and open the drain valve (this could be put on a timer) to start the process.

The main advantage of this type of system is that it is very easy to do water changes and with water that has been prepared. The big disadvantage is that it requires both a sump and a storage tank. You could skip the storage tank and have the R.O. go directly into the sump, but then you cannot aerate, heat and add minerals before changing the water.

ChefKeith- I think that the above consists mostly of your ideas pieced together from other threads. Do I have anthing wrong? Is this a sensible system or are there things that I have missed or that you would do differently?

Emma- You have commented in other threads that your R.O. system is now set up to do large water changes twice a day? You must have a very good working system. Would you describe how your system is set up to do your water changes?

Any comments, ideas, criticisms, etc, that anyone can provide will be appreciated.

Thank you.

Keith

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chefkeith
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Post by chefkeith » Sun Mar 04, 2007 10:39 pm

Sounds like a good plan to me.

I haven't thought my plans completely through yet. I was hoping to just copy off of somebody else's system, but haven't found a perfect match yet.

I was thinking of getting a few ATO kits, that comes with a controller.

Here's some links that I saved-

Auto top-off Controller--Dr. Fostersmith
http://www.jbjlighting.com/sys_ato.html
http://www.tsunamiaquatic.com/catalog/i ... 896498.htm
http://www.aquaticeco.com/index.cfm/fus ... s/ssid/353
http://members.cox.net/kyledugger/reef/ ... witch1.htm
http://www.top-off.com/listitems.php?ca ... 48502c5e66

edit: changed the long fostersmith link so it would fit most pages without scrolling left/right.
shari2

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Keith Wolcott
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Post by Keith Wolcott » Mon Mar 05, 2007 9:20 am

Excellent links ChefKeith. Thank you. I especially like the DIY version. With these types of switches it should not be too hard to design a good system.

You got me thinking about continuous feed water change systems. So here is a completely different plan that has the advantage of getting rid of the large sump and storage tank.

Still have a sump but it does not have to be very large.

Mount a small storage tank (10 g?) above the sump which is fed by an R.O. filter.

Have a drain with a valve that can be adjusted to drip down into the sump at the desired rate.

Have a two float system in this upper tank that refills it from the R.O. filter every time it gets 90% empty.

In the sump have an overflow to a drain where water enters the sump from the aquarium and have the input drip from above be near where the water exits the sump to the aquarium.

This is simpler than the previous plan at the start of this thread and requires much less volume in the sump and extra tank. The water in the storage tank could be aerated, but heating is not necessary since it will go into the system so slowly that a sump heater will heat it. The only problem to solve is adding minerals to the R.O. I am not sure of the best way to do this but I have this image of a toilet bowl cleaner. I once (19 years ago) saw a neat device in a toilet tank that would add a teaspoon of toilet bowl cleaner to the water with every flush. It was entirely powered by the lowering and raising of the water. The same could be done in the storage tank with a teaspoon added every time the tank is refilled with R.O. water. Or surely there are more modern dispensing devices that are available. But often, simplest is best.

Comments please. I would appreciate hearing from those that have working systems so that I don't repeat all of the same mistakes. Or if there are links that already discuss this that I have not found please point me in the right direction.

Thank you.

Keith

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chefkeith
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Post by chefkeith » Mon Mar 05, 2007 11:01 am


chris1932
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Post by chris1932 » Mon Mar 05, 2007 1:27 pm

How big is your tank?
What is the water volume that your RO will produce?

I have a constant drip RO feed and overflow on my undrilled 150 tall. I just meter RO water to the tank at 70-90ml/min. I have a micro paristaltic pump that meters a dilute solution of plant nutrients and trace elements that runs once when the lights turn on and once when it turns off. If you want I can take some photographs.
There are pictures this tank setup on the freshwater fourm.
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Emma Turner
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Post by Emma Turner » Mon Mar 05, 2007 6:03 pm

Hi Keith,

The thread that you referred to where I spoke of 2 large RO water changes per day, was talking about our softwater system at the shop where I work. We also have our own RO unit at home for our 1000 litre clown tank, and I'll explain how both work.

The systems at work are commercial systems which are filtered by pressurised sand filters run by external pumps (this is in addition to other filtration). When carrying out a water change, we simply open a waste valve and backflush the filter, which lets out the waste water to a drain. It backflushes at a rate of about 50 gallons per minute and because the process is so quick, it is supervised at all times. We then close the valve and fresh (pre-heated, remineralised) RO water is siphoned in via gravity from a header tank until the system is filled to the correct level. This siphon is turned on and off manually. The RO unit we use at work produces 600 US gallons per day, which gives enough for 2 large water changes on the softwater system, plus enough to sell to customers each day (we are also in a very hard water area here).

At home, we have a 50 US gallon per day RO unit, which fills into a large water butt. To carry out a water change, we use a large bore hose to siphon water out of the aquarium, through our patio doors and out onto the patio/garden. When we have taken the level down enough, we stop the siphon and attach the hose up to another length of hose which in turn is attached to a submersible pond pump situated inside the RO water butt. We then just flick the switch and fresh (pre-heated and remineralised) RO water is pumped across and into the tank. The whole process literally only takes a few minutes. In the summer, when our unit is producing a very good quantity of RO water, we carry out a 10% water change on the tank 4 or 5 times per week. In the winter when our unit is not producing quite so much water, and it takes longer to warm the water up, we drop to changing 10% twice per week. Our nitrates are currently running at less than 20ppm, and in the summer, this level drops to virtually zero. This is with 40+ clown loaches in this aquarium.

If you're going down the automated route, it might be worth your while looking at some of the marine suppliers. A German manufacturer Tunze (we believe they sell to the US) do alarms and cut-off systems in the event that your auto top up system should fail.

Hope this helps, and good luck,

Emma
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Keith Wolcott
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Post by Keith Wolcott » Mon Mar 05, 2007 6:04 pm

ChefKeith- Thanks for the link. It has some good ideas.

chris1932- My tank is 75g (it had been set up for 11 years, but now I am starting over). I am still looking at R.O. filters but was thinking of getting one that produces 100 gpd. I want to get this tank set up to use the R.O. water, but also with a view to using it for a 250g tank in a year.

I am interested in how you accurately meter the water into your tank and how the micro paristaltic pump works. I will take a look at the freshwater forum and see if I can find your pictures. Thanks.

Keith

chris1932
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Post by chris1932 » Mon Mar 05, 2007 9:23 pm

Keith
The flowmeter is a Blue-White Ind F-512-E It is scaled 10-100 ml/min and it is accurate to +or- 1ml/min. It has a small pin valve on the top to set flow rate. Here is a link
http://www.bluwhite.com/flowmetersacrylic.htm
They cost around thirty bucks each.

The pump for macro nutrient and trace minerals is a Stenner tripple head so it is doing tripple duty. I use it because it was free. They are disgustingly expensive. Link to pump
http://www.stenner.com/prod-t44jh1-summary.htm

I am working on a small PLC control for lights,pumps,pH,Co2, and monitoring. Its an older Allen & Bradley sl500 I picked out of the trash.
Hello all from Happy River
I have lost count of how many tanks I have

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Keith Wolcott
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Post by Keith Wolcott » Tue Mar 06, 2007 8:59 am

Chris
Thanks for the information and the links. You have quite a nice setup. I looked at your pictures on the freshwater forum. You have a beautiful tank and beautiful fish.

Keith

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helen nightingale
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Post by helen nightingale » Tue Mar 06, 2007 12:14 pm

Hi Keith

i know this isnt very advanced or automated, but here's what i do, as its a cheap alternative. like Emma, i now have a long hose to put the dirty water out the window. i have a water storage tank mounted at the top of the airing cupboard, above the house water hot water tank. i put a heater and a small pump inside, and i have an overflow pipe at the top, going into the drains, just in case. as the airing cupboard is quite warm, i dont need the heater on with the central heating switched on, as the water is coming out at 25 C at the moment, and i can mix the minerals well with the pump on rather than stirring. as the tank is high up, i can run the water into the tank by gravity.

please let us know how you get on :D

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Keith Wolcott
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Post by Keith Wolcott » Tue Mar 06, 2007 1:54 pm

Thanks Emma and Helen. I rather like your methods.

A continuous drip method has the advantage that it just happens after it is all set up. But things can go wrong. The overflow can fail. Even with a backup float to shut it down, the backup could fail. If the electricity goes off, you have to be sure that any valves that then fail to close or open do not cause a disaster. Also it takes more water to do a continuous drip. I just calculated (actually I assigned it and we did it in my calculus class) the rate of the drip required to be equivalent to a 10% per day water change. It requires 5% more water. Not a lot, but still a factor. Going from weekly to daily water changes is worse in that it requires 34% more water to get the same effect (this calculation assumes no new waste products enter the tank. It is not hard to change that assumption, but I do not know what rate of pollution input to use. I'll check how much effect it has for various cases.).

With your systems, Emma and Helen, you manually, but very quickly do a water change. It only takes a few minutes and only involves starting a siphon and then a pump (or gravity fed). Not much can go wrong and you are there to handle it if it does. It is similar to my first plan at the beginning of this thread, but removes the sump which greatly simplifies things. I also like the idea of siphoning the water out to the yard. The flowers in my front yard will really like that along with the R.O. waste water that the filter produces.

Questions:

1. How large is your siphon hose? Pretty big to do the 1000 L loach tank I imagine.

2. What is everyones opinion of UV. I have read some good things about it, but it could also just be an added unnecessary gadget. It seems like it is just a little bit of extra insurance, but it is not clear if it is worth it. I ask this because it affects whether or not I want to have a sump. I like the idea of having a heater and possibly UV in the sump so it is out of site.

Thanks for everyone's help. I appreciate it.

Keith

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chefkeith
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Post by chefkeith » Tue Mar 06, 2007 3:13 pm

Thanks for math figures on the continuous drip system. I'm glad someone could do the math.


I use a 3/4" hose for removing water, and a 1/2" Python gravel vac hose for adding water.

About UV, I now run mine 24/7.

The UV does add a few degrees of heat to the water in my tanks.

I thought I noticed some good effects from UV. My Boesemani Rainbowfish have had far fewer problems with columnaris lately.
But now I'm hearing that bacteria, like Columnaris, may be more prone to tanks that are high in iron. I was using fertilizers, that contained iron, back when the fish were having problems. So now I'm not sure why these fish are much healthier now. It's either the UV or that my water is much lower in iron.

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Post by Emma Turner » Tue Mar 06, 2007 4:34 pm

Hi Keith,

We use hose of an inch internal diameter for siphoning water out of the big loach tank. It's a pretty long length to run it outside, but it's a one-off expense.

We also continually run a UV steriliser on this tank. Previous (slightly heated :wink: ) discussion on the pros and cons can be seen here: http://forums.loaches.com/viewtopic.php ... highlight=

Emma
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Keith Wolcott
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Post by Keith Wolcott » Tue Mar 06, 2007 9:52 pm

Emma and ChefKeith- Thanks for the siphon sizes and the UV info and thread link. I should have found the link myself, but I missed it somehow when I searched.

I have some thinking to do now to decide just how I want to set things up.

Keith

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Keith Wolcott
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Post by Keith Wolcott » Thu Mar 08, 2007 1:42 pm

I worked out the calculations for how different types of water changes compare to each other. I gave just a couple of example figures earlier, but had not taken into account any input pollution. I have now added this more realistic assumption. I have assumed that the tank pollution has stabilized. That is, that the number of fish, the feeding, and the water changes have remained the same for a long period of time so that the pollution has reached an equilibrium. The table shows how to switch water changes from, for example, weekly to daily or to a continuous drip, and know how much water to change to get the same effect so that your pollution level remains stabilized at the same level as before.

As an example, If you change 50% of your tank each week, look at the vertical column under "1 week" and go down to the row with a 50. Then if you move left of right on that row you see how much water you should change for different time periods. If you want to change water every 2 days the table says that your should change 22.2% of your tank. If you want to use a continuous drip then you should feed in .60% of your tank per hour.


Image

The second table below shows how much water usage you have per day as a percent of your tank size.

Thus, for example, if you currently do a 50% water change every week, the table shows that you are using 7.14% of your tank every day. If you switch water changes to every day (using the top table) you will use 12.5% of your tank every day. If you switch to a continuous drip, you will use 14.29% of your tank every day. Thus continuous drip uses twice as much water as changes once per week.

Conclusions: Changing water more often requires more water. Changing water less often allows more variation in the pollution level and then changing water is more of a shock to the fish. This last point maybe requires some explanation. The assumption for table 1 above is that the pollution has stabilized. That means that after each water change the pollution is at a concentration of P ppm. Just before a water change, the pollution level has gone up. In the example of 50% water change per week the pollution level oscillates from P up to twice P and then back down to P when you do the next water change. The shorter the period between water changes, the smaller this spike is (and doesn't exist at all if using a continuous drip).

Thus, I am no longer thinking of using a continuous drip because it uses so much water. I will opt for maybe changing water every 3 days. At 3 days the twice P spike above is only 1.43 P.


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One other table that I want to create is a table that shows how to do different water changes to change the level of pollution. For example, if I do nitrate tests and over time it has stabilized at say 50 ppm, what % water change should I switch to in order to make it restabilize at 20 ppm?

Remark 1: How are these tables related the ChefKeith's table which gives times and pollution plateaus? ChefKeith's table and spreadsheet calculates how long it takes the pollution level to stabilize or reach a plateau, and gives the plateau level. The above tables assume that the plateau has already been reached and that we just want to switch to a different water changing scheme and maintain the same pollution plateau.

Remark 2: The tables above assume that the water you are using to put in the tank has no pollution. Thus, they will apply best if R.O. water is used or if the pollution that you are concerned with does not occur in your input water. If you are interested in TDS and are not using R.O. water then you should use ChefKeith's table to keep track of TDS.

I hope that these tables are of some use. If there are questions, please ask. The math involved is algebra for the periodic intervals, and second semester calculus involving mixtures and separable differential equations for the continuous drip. I will gladly provide details of the methods.

Keith

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