Just curious would a CO2 feeder work well?

[salinda]

I still use quite a bit of muriatic acid. I really have to stay on top of it. Every year I have to lower TA quite a bit and then the usage drops to maybe 1/2 gallon a week instead of 1 gallon a week, but only if I stay on top of it. I'm considering an auto-feed system of some type, and I was researching and came across a CO2 gas system that looks very simple. How would it work with pool chemistry in a SWG system?

 

[JasonLion]

Yes, a CO2 system would help. The PH is going up because CO2 is outgassing. If you maintain the CO2 level by adding more to compensate for what outgasses the PH change will stop.

There may be simpler ways to achieve the same result. It is usually possible to balance your chemistry so that CO2 outgassing is minimized. If you post a full set of test results someone here might be able to suggest something.

 

[salinda]

I am just now "starting up" for the spring. I ran out of r-0012, one of the CH reagents, so I couldn't test my CH today. My CH has been high for the past couple of years and I am probably due for a partial drain. Chem Geek (richard?) has helped me a lot in the past. I try to keep my TA very low and my pH around 7.6 to compensate for the high CH (~520-580 in past years). I am hoping that the massive volume of rainwater that was added to my pool this winter might change the chemistry a little and reduce the amount I will have to drain. Until I know that, I won't really know what I am aiming at this year. I don't want to add too much before a drain and refill, thus wasting money.

Also, I am trying to convince my husband that a cover might prolong our pool season, mitigating the effect of the cool nights, and also reduce acid demand. He doesn't want the extra hassle.

 

[Guest]

CO2 feed systems do help keep pH down but at the expense of TA. They can cause the TA to rise in actual use. This would then nessesate the use of acid to lower the TA. So they won't really eliminate your acid usage, just postpone it.

 

[Aquaman95]

That one looks like it should diffuse pretty well so you shouldn't need much acid for TA control.

Do be careful though, it does require the use of a compressed gas cylinder. Chain it to the wall. You don't want it to topple over and break the valve off the top. They can become CO2 powered rockets. I think CO2 cylinders are about 3,000 PSI.

Also, don't put it in an enclosed room. CO2 is heavier than oxygen and can displace all the oxygen out of a room. Too much of it leaking in an enclosed room can be a deathtrap...quite literally:

http://spewingforth.blogspot.com/2005/0 ... -feet.html

 

[salinda]

I'm checking on pricing now. I may hold off. This would be all outside on the north side of a building so it is in the shade. That is how my pool equipment is situated currently.

 

[Aquaman95]

I just re-read my post and I'm afraid it may have come off a bit alarmist.

Don't get me wrong, it can be a good system I just wanted to bring up a couple things to be careful of.

I'd love to hear how much they want for that system and which CO2 regulator they are using. Good regulators that don't freeze up and don't blow diaphragms can be spendy.

 

[salinda]

The system was quoted to me at $855 for a two cylinder system that he would recommend for my pool. I am holding off for now. I have to admit though that a little freedom from the acid dumping would be much appreciated.

 

[Aquaman95]

If one of your main goals is to avoid adding acid by hand and automating the process somewhat you could just purchase a peristaltic pump to inject the acid. The come with timers or feed rate controls so you could set it to trickle feed when the pool is on. $200-$400 is what you could expect to pay for a new one. You can find good used ones on ebay cheap as well. For acid, annual feed tube changes and tubing/roller inspection is about the only maintenance.

 

[mas985]

I have a SWG which means that my PH is constantly going up. I have tried Borax and keepinig my TA low but with high TA fill water, it is a never ending battle. So I was looking for a simple acid injection system which would slowly drip acid into the pool much like an IV drip system. A peristaltic pump was certainly one option but I decided to try a homemade system first. So I wanted to share with everyone what my experience has been.

For the past couple of months, I have been testing a homemade semi-passive acid injection system (all plastic) which costs < $30 for me to put together. It uses a 7 Gallon camping water container with several drip irrigation buttons for flow control, plastic fittings and hose. It connects to the suction side of the pump which is why I call it a semi-passive system since it relies on the pumps suction and the drip irrigation buttons control the flow rate. I am still testing it out but this is what I have found so far.

The draw rate is easily controlled by adding or removing buttons. Currently, I have 6 inline which makes for a 16 oz/hr draw rate and I only need to refill the container every 4 weeks or so. Also, it means that I will have a constant flow of acid solution to help keep the PH balanced and it is fairly maintenance free.

The downside is that depending on the valve orientations, the flow rate changes slightly. However, I have found that this has not been a problem since it seems to average out some over the four weeks. So far I have been able to keep the PH between 7.4 and 7.7.

The acid dilution in the container is currently at 7:1 but expect that I will have to increase this during the summer for the longer pump run times. Because my normal flow rate is about 88 GPM, the actual dilution rate in the skimmer basket of the pump is about 295000:1 which means that the PH level in the equipment is slightly lower than the pool PH but probably not more than .1 lower.

So far it looks like it will work well over time but it really needs to be tested during the summer months to see if I can get the draw rate and dilution dialed in properly. A large water container would certainly help and allow for more flexibility.

If anyone is interested in duplicating this setup, I would be happy to help in anyway I can.

 

[Aquaman95]

I have a SWG which means that my PH is constantly going up. I have tried Borax and keepinig my TA low but with high TA fill water, it is a never ending battle. So I was looking for a simple acid injection system which would slowly drip acid into the pool much like an IV drip system. A peristaltic pump was certainly one option but I decided to try a homemade system first. So I wanted to share with everyone what my experience has been.

For the past couple of months, I have been testing a homemade semi-passive acid injection system (all plastic) which costs < $30 for me to put together. It uses a 7 Gallon camping water container with several drip irrigation buttons for flow control, plastic fittings and hose. It connects to the suction side of the pump which is why I call it a semi-passive system since it relies on the pumps suction and the drip irrigation buttons control the flow rate. I am still testing it out but this is what I have found so far.

The draw rate is easily controlled by adding or removing buttons. Currently, I have 6 inline which makes for a 16 oz/hr draw rate and I only need to refill the container every 4 weeks or so. Also, it means that I will have a constant flow of acid solution to help keep the PH balanced and it is fairly maintenance free.

The downside is that depending on the valve orientations, the flow rate changes slightly. However, I have found that this has not been a problem since it seems to average out some over the four weeks. So far I have been able to keep the PH between 7.4 and 7.7.

The acid dilution in the container is currently at 7:1 but expect that I will have to increase this during the summer for the longer pump run times. Because my normal flow rate is about 88 GPM, the actual dilution rate in the skimmer basket of the pump is about 295000:1 which means that the PH level in the equipment is slightly lower than the pool PH but probably not more than .1 lower.

So far it looks like it will work well over time but it really needs to be tested during the summer months to see if I can get the draw rate and dilution dialed in properly. A large water container would certainly help and allow for more flexibility.

If anyone is interested in duplicating this setup, I would be happy to help in anyway I can.

That can work but you run a chance of corroding any metal inside the pump and certainly your heat exchanger. I'd be most concerned about the heat exchanger.

 

[mas985]

That can work but you run a chance of corroding any metal inside the pump and certainly your heat exchanger. I'd be most concerned about the heat exchanger.

That is one of the reasons that the dilution is so high going into the pump. I have measured the PH coming out of the return jets and it is not much lower than the PH of the pool itself ususally > 7.4 PH. So I don't think that will be an issue.

One more thing to add about dilution. This is in fact safer than adding acid once a week like I did before. So if I am adding the equivalent of 32 oz of acid per week and I have a 21000 gallon pool. If I add it to the deep end, the dilution ratio would be lower than 84,000:1 while the pump injection method is 295,000:1 which means I actually have less acid traveling throught the equipement than if I added it all at once to the pool. This is the benefit of continuous injection.

 

[salinda]

If one of your main goals is to avoid adding acid by hand and automating the process somewhat you could just purchase a peristaltic pump to inject the acid. The come with timers or feed rate controls so you could set it to trickle feed when the pool is on. $200-$400 is what you could expect to pay for a new one. You can find good used ones on ebay cheap as well. For acid, annual feed tube changes and tubing/roller inspection is about the only maintenance.

I have thought about this, but I have a large pool and I am assuming the feed tank would have to be somewhat large. My equipment is outside and I have a dog and kids and I prefer to have my acid locked in a cabinet than hanging around in a tank that could be knocked over. Also, where would it feed in? Between the pump and filter, at the return line to the pool? The return line to the pool is right after the swg. Wouldn't that cause a dangerous problem, mixing acid and base?

 

[JasonLion]

The AutoPilot Total Control system puts the acid feed a little before the SWG cell and after the heater (if any).

 

[mas985]

I have thought about this, but I have a large pool and I am assuming the feed tank would have to be somewhat large. My equipment is outside and I have a dog and kids and I prefer to have my acid locked in a cabinet than hanging around in a tank that could be knocked over. Also, where would it feed in? Between the pump and filter, at the return line to the pool? The return line to the pool is right after the swg. Wouldn't that cause a dangerous problem, mixing acid and base?

The tank I use has a screw on lid and is water tight so even if it is knocked over, it will not spill. If you are still worried about having the tank exposed, you could aways find one that fits in a lockable deck box or cabinet. Also, your pool is only slightly larger than mine so you could just go with a lower dilution ratio and still use the same size tank.

Also, as long as the feed rate is very slow, it really doesn't matter where you feed the acid. As I pointed out before, as long as the acid is well diluted, there is no chance of a chemical reaction or corrosion of the plumbing. The amount of acid actually added is so small compared to the normal water flow that the resultant mixture is only a sightly lower PH.

[EDIT] I wanted to add that there is dilution in both the tank as well as when the solution is injected into the plumbing system. Pool plumbing has very turbulent water flowing through it so anything that is injected will be quickly mixed with the high rate flowing water. For my case, the water flows a 88 GPM while a 7:1 acid solution flows at 0.0021 GPM which yields a dilution ratio of 295,000:1, a very small amount of acid.

 

[Aquaman95]

Thanks for clarifying that mas. I can promise you not diluting the acid beforehand will likely result in heater core destruction, I can appreciate your logic on the pre-dilution and it may prevent the problem. I'm just very nervous about it...I accidentally installed acid injection pre-heater several years ago in a very large pool with a complex plumbing system. After writing the check for a new heat exchanger on a 1.1 million btu boiler I can assure you I'll never make that mistake again!

Salida - Acid demand on a 35k gallon residential pool is probably low enough that you could just use the 1 gallon jug as the feed container or get a more solid 5 gallon sealable jug from an ag store...most of them carry chemical tanks.

I would assume Autopilot installs their acid pre-cell/post heater to help clean calcium off the plates but I'm sure Sean could verify that and whether you can install acid injection pre-cell on their other units. I'd bet you could and pre-cell/post heater would be ideal.

 

[mas985]

Thanks for clarifying that mas. I can promise you not diluting the acid beforehand will likely result in heater core destruction, I can appreciate your logic on the pre-dilution and it may prevent the problem. I'm just very nervous about it...I accidentally installed acid injection pre-heater several years ago in a very large pool with a complex plumbing system. After writing the check for a new heat exchanger on a 1.1 million btu boiler I can assure you I'll never make that mistake again!

Ouch, that's gotta hurt. I can understand your concern.

However, I am pretty confident that I will not run into the same problem since I have taken some precaution in making sure PH levels do not get too low. I measured the PH of the water coming out of the equipment with the acid injection system I described and it is above 7.5 which is no where low enough to damage anything. The key factor is injecting the solution at a slow enough rate to keep dilution ratios high.

Some peristaltic pumps will inject faster than others and probably well above the injection rate that I am doing. So these injection systems must cycle the pump on and off over time to achieve the desired PH. When the pump is on, this tends to make the PH much lower so more caution is required for the installation which is why they recommend post heater installation. The method I was describing has injection rates much lower thereby causing only a small drop in PH but continuous.

 

[Aquaman95]

Thanks for clarifying that mas. I can promise you not diluting the acid beforehand will likely result in heater core destruction, I can appreciate your logic on the pre-dilution and it may prevent the problem. I'm just very nervous about it...I accidentally installed acid injection pre-heater several years ago in a very large pool with a complex plumbing system. After writing the check for a new heat exchanger on a 1.1 million btu boiler I can assure you I'll never make that mistake again!

Ouch, that's gotta hurt. I can understand your concern.

However, I am pretty confident that I will not run into the same problem since I have taken some precaution in making sure PH levels do not get too low. I measured the PH of the water coming out of the equipment with the acid injection system I described and it is above 7.5 which is no where low enough to damage anything. The key factor is injecting the solution at a slow enough rate to keep dilution ratios high.

Some peristaltic pumps will inject faster than others and probably well above the injection rate that I am doing. So these injection systems must cycle the pump on and off over time to achieve the desired PH. When the pump is on, this tends to make the PH much lower so more caution is required for the installation which is why they recommend post heater installation. The method I was describing has injection rates much lower therby causing only a small drop in PH but continuous.

I agree and I hadn't caught on fully to the theory of your system until I read that last post. Peristaltic pumps (particularly on automation systems) are designed to come on, quickly pump in the chemical to make the adjustment and go off again; while still avoiding overshooting. Some proportional systems wind up "drip feeding" like you are describing but that's not normally the goal.

 

[EskimoPie]

Mas, I would very much like to see some pictures of your setup. While my pool is very nearly maintenance free with the SWCG and in-floor cleaning, I still would like to reduce it even further. Since this thread is titled about a C02 feeder, perhaps you could start a new thread on automatic acid injection. What I'd really love to see is a commercial product for automated acid injection, but seeing how the industry is lacking such a product I might just build my own as you did. Thanks for the info!!!

Edit: I did read through the OP's link to the inpHuser product and it sounds very attractive. The major drawback for me is the need to re-fill the C02 tanks. I can buy muriatic acid a the grocery store a block away from my house. To refill C02 tanks I would have to drive 10+ miles each way to a welding supply store. That hassle alone would negate the benefits of the system for me.

 

[mas985]

Mas, I would very much like to see some pictures of your setup. While my pool is very nearly maintenance free with the SWCG and in-floor cleaning, I still would like to reduce it even further. Since this thread is titled about a C02 feeder, perhaps you could start a new thread on automatic acid injection. What I'd really love to see is a commercial product for automated acid injection, but seeing how the industry is lacking such a product I might just build my own as you did. Thanks for the info!!!

I'll start a new thread for this.

Also, HASA does have an acid system like the liquidator but requires dry acid and must be used with the liquidator. They don't advertise it much but it is available. I wanted something to use for muriatic acid.