Continuous water change???

[Dashiki]

The one factor that everyone seems to overlook is a continuous water change is not a true water change and I'll explain. I have a 180 and I like to change 35 - 40 every couple of weeks (don't like it but need to). Of course we do this as a way to export excess nutrients. First, I use water changes to clean a lot of my tank such as siphon debris out of the sand, and chaeto and every so often I'll drain and clean my sump and use the water change water to refill it. Plus when water is being returned it is nice to use the return hose to clean off your rock work. Second, if you figure that you need to change say 28 gallons per week and change 4 gallons per day, then you are actually not changing 28 gallons of nutrient filled water. Using a 100 gallon tank, if you take out 4 gallons and add 4 gallons, the next day you have 96 gallons of "old" water and 4 gallons of new. You can't pull out just the "old" water, so you will actually be pulling out some water you just put in yesterday. And after adding another 4 gallons every day, you will be pulling out more and more "new" water. IMO defeats the purpose of the water change.

I've read about one big water change opposed to several small ones; the lessor shock on the corals and fish and a more consistent replacement of essential elements. I attempted a 5 gallon every third day method, but I like the 35 gallon every other week change.

Thats not exactly how the math works. Yes after two days its not much of a difference. But if you followed the math then with that equation we would be removing the same four gallons we put in just a day ago.

you would need to look at a nutrient you are trying to control like nitrates. if your nitrates are 5ppm and you have a 100 gallon tank then changing five gallons would reduce it by 5% ( you would need to add back in you daily rise in nitrates for accuracy ) then on day two you have 4.75ppm ( plus your daily rise in nitrate ) and so on.

you could calculate the correct amount to change everyday to keep you levels flat and near zero.

as for the float switches you program your controller to not turn on your ato during the time of the change so using float switches is a viable option.

 

[docs911]

I have been doing a continuous water change system for about three years. I have a litermeter III with a second pump. One pumps tank water out, and another pumps fresh salt water in. I have the incoming water slightly more than the outgoing to factor in the water taken out by the skimmer. I have a separate litermeter on a float switch and it is used as a automatic top off. The outgoing salt water from the tank is plumbed into the house drain.

Yes, as the tank water is pumped out, I am pulling out a small amount of newer salt water. BUT, the water changes are essentially automatic. All I have to do is make sure my vat is full of new salt water and periodically check the tank salinity. The system makes my weekly upkeep so simple.

 

[Daniel@R2R Verified Admin]

Ok, I'm backing off of this thread. I think it has a totally title wrong. Replacing evaporated water via an ATO we all do. Water changes are to export excess nutrients. Replacing evaporated water does not export nutrients. I've seen people that have systems that don't believe in water changes and their tanks look great. However, I'm a generous feeder and as said above, I use water changes to export nutrients, clean sand, and when returning the "new" water, I like to blow it over my corals. Taking a gallon or 2 of water out of your system and using your ATO to replace it, to me and it's just my opinion is not a water change, nor is replacing evaporated water.

To me, a water change is removing a significant amount of nutrient filled water (10% is significant in my book) and replacing it with new, "clean" water. Again, a good reefer should use this time to clean the sandbed, sump, etc.

Actually, you are right on topic with what I intended. The discussion is of a "continuous water change" and while ATO is something to be considered in the equation (for example, we don't want to replace water pulled for this with RODI water by accident...which would happen if the ATO is left on with no way of switching it or controlling it), but the idea is continuous replenishment of trace elements. Your point about export is a good one, and I would say that if one did use a continuous water change system, then something else would have to be done for waste export (strong skimmer, carbon, GFO, vodka dosing, refugium, etc.). The question I would ask is if my nitrate and phosphate levels are solid (via these other methods of waste export), then why not use a continual system for replenishing trace elements? ...couldn't this be a way to eliminate the need for dosing?

 

[Lawnmower]

Why not drop the ATO altogether?

-Mix your salt in a big reservoir

-Add estimated evaporation RO water for a week

-Plug an overflow in you sump to your house drain

-Set a drip line with a cheap aqualifter so that you empty your reservoir during the week

Voila

 

[Daniel@R2R Verified Admin]

Interesting theory. Might be a little tough to estimate the evaporation rate. I'd probably still recommend an ATO run off of a controller with salinity probe. If you use your drain idea, then the ATO could just dilute the saltwater to the correct spec with excess water draining off as the ATO water gets pumped in.

 

[Lawnmower]

If you need absolute stability then you could hookup with a salinity probe and a controller with the same setup I described.

You could add setup alarm
timers on the controller for redundancy.

I currently use an aqualifter drip line as an ATO and it works very well.

My house drain is far from my tank so I cannot easily test this idea out.

 

[Lawnmower]

Sorry MdBannister. Just got your idea. Yeah it might be simpler to just hook an existing ATO

 

[Diesel]

interesting subject.

 

[bcfd144]

Ive been thining about this also

Ive been thinking of doing this also. I have a 275 gallon system and Id like to change at least 8 gallons per day. That would be 55 gallons a week. 20%. So my idea. I would need to solve three things. Getting 7 gallon of dirty water out. Putting 7 gallons of fresh saltwater back in. And keeping the ATO from coming on while doing it. I have a Reefkeeper Controller on my tank. So I should be able to do this easily. First, Hook up two dosing pumps to my reefkeeper system. Set one to drain out dirty water, set the other to put back in fresh salt water. 7 gallons each. (test to make sure the head loss is the same so that the same amount of water going out comes back in. Then I can set the Reefkeeper to shut off the ATO system when the Dosing pumps are active. This way, I don't have to worry about my ATO coming on when the water change is happening.

 

[bcfd144]

Ive been thinking of doing this also. I have a 275 gallon system and Id like to change at least 8 gallons per day. That would be 55 gallons a week. 20%. So my idea. I would need to solve three things. Getting 7 gallon of dirty water out. Putting 7 gallons of fresh saltwater back in. And keeping the ATO from coming on while doing it. I have a Reefkeeper Controller on my tank. So I should be able to do this easily. First, Hook up two dosing pumps to my reefkeeper system. Set one to drain out dirty water, set the other to put back in fresh salt water. 7 gallons each. (test to make sure the head loss is the same so that the same amount of water going out comes back in. Then I can set the Reefkeeper to shut off the ATO system when the Dosing pumps are active. This way, I don't have to worry about my ATO coming on when the water change is happening.

But at the same time, the issue of changing small amounts a day vs. Larger amounts is in question. I could also set this up to where is just does a once a week 20% water change.

 

[Velodog2]

But at the same time, the issue of changing small amounts a day vs. Larger amounts is in question. I could also set this up to where is just does a once a week 20% water change.

Which would be significantly more effective at removing bad water. But it would also let waste product levels increase more in the interim. That is the trade-off. It is stability vs efficiency. Where do you want the line drawn?

 

[Daniel@R2R Verified Admin]

Which would be significantly more effective at removing bad water. But it would also let waste product levels increase more in the interim. That is the trade-off. It is stability vs efficiency. Where do you want the line drawn?

Exactly. This system is all about stability. And over the long term, this also becomes efficient. If I am continually changing water, then sooner or later the system is constantly renewed. If one uses other methods of waste removal, then export is no longer a major concern.

 

[Velodog2]

I'm not sure I understand your assertion of efficiency increasing over the long term, or what you mean by eventually becoming constantly renewed.

 

[Lawnmower]

I have been thinking.

Continuous water change could be the only export mechanism for a nano or pico tank.

Lets say you setup a 10 gallon with only a bit of live rock, sand and circulation.

Weekly mix 50 gallons of saltwater and continuously change during the week.

That's it. You could adjust depending how much natural filtration from the rock algae coral and sand in the thank but that would be it.

Maintenance cost would be salt cost. Lets say 10$ per week.

 

[Daniel@R2R Verified Admin]

I have been thinking.

Continuous water change could be the only export mechanism for a nano or pico tank.

Lets say you setup a 10 gallon with only a bit of live rock, sand and circulation.

Weekly mix 50 gallons of saltwater and continuously change during the week.

That's it. You could adjust depending how much natural filtration from the rock algae coral and sand in the thank but that would be it.

Maintenance cost would be salt cost. Lets say 10$ per week.

I like this idea too. I'd even think you could just setup to change whatever the nano's total volume is over the course of a week. For example, on a Biocube14 change 14 gallons.

 

[Lawnmower]

Yes 100% weekly might be enough, but if you assume no other filtration than water change and calculate daily dilution, doing this would leave 35% of whatever was in the water at the end of the week.

Doing 500% over a week leads to 0.02% residuals also with a daily dilution calculation.

But you also need to take care of food.

But since there will be some filtration from the Rock and anything that grows who knows what the real number needs to be.

So 500% was just a starting number as it dilutes pretty much anything that was in the water at the beginning of the week.

 

[Daniel@R2R Verified Admin]

Makes sense.

 

[KSzegi]

Just thought I would add an article of interest to the topic ... currently giving the daily changes a try using liter meters for both water change and ato.

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

 

[Lawnmower]

Interesting! He suggest minimum 50% daily change to maintain calcium and alkanity in a growing reef.

Is there an aquarium husbandry topic that RHF hasn't touched ?

 

[Velodog2]

Farley is mind-bogglingly thorough and that was a great reference! It brought to my attention a potential problem with my current maintenance regime that I will now fix. Thanks!