First off I have to say that running a dosing pump for Calcium and Alkalinity has been one of the best moves that I have made for my SPS corals. This is going to be a long post, but I think that it is valuable for anyone dosing to read.
When I started to dose, I began by simple adding a small amount (about 25 ml) every morning. This was a great way to get into dosing and learning how to test my levels of KH and Ca. After about a few months of dosing by hand I began to consider dosing pumps, and found a large range in price. From what I had read I did not want to rely on any of the cheaper dosing pumps as they have been known to fail and destroy whole tanks. For the record, any dosing pump can fail and take out your whole tank if you don’t have the right precautions. It took me about a year before I decided to go for the dosing pump.
After doing a large amount of reading on all the options, I found that although the likelihood of a more expensive dosing pump failing was much lower, it was still possible and I couldn’t have that. I decided on the Jebao DP-4 that I picked up for about 70$ on amazon, mainly due to financial reasons, and I can upgrade in the future. Now that I had my new pump I had to decide how I would set it up to create a system of redundancies to limit the risk of a tank crashing failure. As a Mechanical Engineer, one of my jobs is Failure Mode and Effect Analysis (FMEA). This works by looking at all the possible failures, even multiple at the same time and finding out how a system will respond, then finding solutions to avoid these problems.
Take my auto top off for instance, I have a float valve (failsafe 1) on my auto top off pump. (My ATO also has 3 switches (failsafe 2), and the reservoir is also smaller than the volume left in my sump when the return turns off, so that’s a third failsafe on that system). To take it to the next level if the pump runs continuously for more than 2 minutes it sets an error on the Apex and is turned off until I log into to check it out. (4th failsafe) To create a redundant system for dosing I came up with this list of possible failures of the pump (if you can come up with more please share):
1. Syphon from dosing tank to sump
2. Pump stuck on
3. Pump stuck off or incorrect flow
Ill address each of these problems and how my system has created redundancies to prevent a failure from turning into a disaster. I will say that most of these failsafes rely on my APEX controller, the best investment I have ever made for my reef.
1. Syphon from dosing tank to sump
This one is easy.
a. Make sure that the dosing pump that you have has more than one roller in contact all of the time. This will make sure that the tube is always pinched. For most designs this only requires 3 rollers.
b. Locate your reservoir below the water level of the sump chamber / tank that you are dosing.
2. Pump stuck on
This is the dreaded one. I don’t care if you spend 600$ on a dosing pump it can still happen.
a. The first line of defense against this failure is to limit the amount that could potentially be dosed if you have a failure. I do this by having 500 ml dosing reservoirs that I fill to about 250ml about one a week. To make these I purchased rubbing alcohol bottles for about 1$ a piece and modified them by gluing a piece of hard airline tube into their top and adding volume marks on the side. If one of my pumps was to stick on it will only dump a maximum of a weeks’ worth of solution into the tank, for Ca I can live with that and my corals can too. When it comes to KH that would mean about a 3 dKH rise, which is a lot for the tank, but it would probably survive. That’s where failsafe 2 and the apex come in.
b. I had to figure out a way for the apex to determine if too much KH dosing solution made its way to the tank so that it could shut off the outlet for the dosing pump. The only monitor that I have for this is pH, and the apex programing will not allow testing for pH change so I had to develop my own setup using apex outlets. I have currently set up my apex to turn off the dosing pump outlet if I have more than a .2 pH rise in less than a minute. I will go into the pH monitor in another post, but I have tested it and it will sense any dose over 20 ml KH solution at once to the sump chamber right after the pH probe. (This is where I dose, right before the return. That means the dose has to travel through the display before reaching the pH probe.)
3. Pump stuck off or incorrect flow
a. A pump that sticks in the off state or the flow drifts from its calibration will have less impact but will still create problems. My solution for this is the dosing containers. By using small containers, I can monitor my dosing solution consumption down to about 10 ml and daily when I check my tank. I have gotten a feel for how fast they go down and in what ratio to each other. Every day I look at them and see that they are where they should be. If I had it connected to the gallon dosing reservoirs I have no idea how much is being used daily, just that it is slowly going down over the month.
Conclusions
Any dosing pump can fail and kill your reef if the proper precautions are not taken. I believe that anyone who is dosing with a pump should limit the volume of their dosing reservoirs to limit this problem. Only keep enough solution in the reservoir that you would be “comfortable” dosing all at one. If you are one of the lucky ones who has an Apex, set up a failsafe there such as the pH monitor, or come up with something new. If you don’t want to go to the advanced pH rate change monitor, just set it up so if your pH goes over a certain value that is above of its normal range it turns off the dosing pump.
I can say that I am confident in my Jebao dosing pump and will happily run it until it fails, or I have the money to splurge on a nicer pump.
When I started to dose, I began by simple adding a small amount (about 25 ml) every morning. This was a great way to get into dosing and learning how to test my levels of KH and Ca. After about a few months of dosing by hand I began to consider dosing pumps, and found a large range in price. From what I had read I did not want to rely on any of the cheaper dosing pumps as they have been known to fail and destroy whole tanks. For the record, any dosing pump can fail and take out your whole tank if you don’t have the right precautions. It took me about a year before I decided to go for the dosing pump.
After doing a large amount of reading on all the options, I found that although the likelihood of a more expensive dosing pump failing was much lower, it was still possible and I couldn’t have that. I decided on the Jebao DP-4 that I picked up for about 70$ on amazon, mainly due to financial reasons, and I can upgrade in the future. Now that I had my new pump I had to decide how I would set it up to create a system of redundancies to limit the risk of a tank crashing failure. As a Mechanical Engineer, one of my jobs is Failure Mode and Effect Analysis (FMEA). This works by looking at all the possible failures, even multiple at the same time and finding out how a system will respond, then finding solutions to avoid these problems.
Take my auto top off for instance, I have a float valve (failsafe 1) on my auto top off pump. (My ATO also has 3 switches (failsafe 2), and the reservoir is also smaller than the volume left in my sump when the return turns off, so that’s a third failsafe on that system). To take it to the next level if the pump runs continuously for more than 2 minutes it sets an error on the Apex and is turned off until I log into to check it out. (4th failsafe) To create a redundant system for dosing I came up with this list of possible failures of the pump (if you can come up with more please share):
1. Syphon from dosing tank to sump
2. Pump stuck on
3. Pump stuck off or incorrect flow
Ill address each of these problems and how my system has created redundancies to prevent a failure from turning into a disaster. I will say that most of these failsafes rely on my APEX controller, the best investment I have ever made for my reef.
1. Syphon from dosing tank to sump
This one is easy.
a. Make sure that the dosing pump that you have has more than one roller in contact all of the time. This will make sure that the tube is always pinched. For most designs this only requires 3 rollers.
b. Locate your reservoir below the water level of the sump chamber / tank that you are dosing.
2. Pump stuck on
This is the dreaded one. I don’t care if you spend 600$ on a dosing pump it can still happen.
a. The first line of defense against this failure is to limit the amount that could potentially be dosed if you have a failure. I do this by having 500 ml dosing reservoirs that I fill to about 250ml about one a week. To make these I purchased rubbing alcohol bottles for about 1$ a piece and modified them by gluing a piece of hard airline tube into their top and adding volume marks on the side. If one of my pumps was to stick on it will only dump a maximum of a weeks’ worth of solution into the tank, for Ca I can live with that and my corals can too. When it comes to KH that would mean about a 3 dKH rise, which is a lot for the tank, but it would probably survive. That’s where failsafe 2 and the apex come in.
b. I had to figure out a way for the apex to determine if too much KH dosing solution made its way to the tank so that it could shut off the outlet for the dosing pump. The only monitor that I have for this is pH, and the apex programing will not allow testing for pH change so I had to develop my own setup using apex outlets. I have currently set up my apex to turn off the dosing pump outlet if I have more than a .2 pH rise in less than a minute. I will go into the pH monitor in another post, but I have tested it and it will sense any dose over 20 ml KH solution at once to the sump chamber right after the pH probe. (This is where I dose, right before the return. That means the dose has to travel through the display before reaching the pH probe.)
3. Pump stuck off or incorrect flow
a. A pump that sticks in the off state or the flow drifts from its calibration will have less impact but will still create problems. My solution for this is the dosing containers. By using small containers, I can monitor my dosing solution consumption down to about 10 ml and daily when I check my tank. I have gotten a feel for how fast they go down and in what ratio to each other. Every day I look at them and see that they are where they should be. If I had it connected to the gallon dosing reservoirs I have no idea how much is being used daily, just that it is slowly going down over the month.
Conclusions
Any dosing pump can fail and kill your reef if the proper precautions are not taken. I believe that anyone who is dosing with a pump should limit the volume of their dosing reservoirs to limit this problem. Only keep enough solution in the reservoir that you would be “comfortable” dosing all at one. If you are one of the lucky ones who has an Apex, set up a failsafe there such as the pH monitor, or come up with something new. If you don’t want to go to the advanced pH rate change monitor, just set it up so if your pH goes over a certain value that is above of its normal range it turns off the dosing pump.
I can say that I am confident in my Jebao dosing pump and will happily run it until it fails, or I have the money to splurge on a nicer pump.
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