Total Control Peristaltic pump acid ratio

[Belldiver]

Anybody know why we cut the acid down 1/4 for this pump? Is it because the plastic tubing can't take the high concentration? Or the PVC? Or is it just to not over treat the pool? I'd like to strengthen the ration to 1/3 if possible so the pump cycles less. Would this hurt anything?

This is a fairly large pool (~30K) so I think it can handle the acid without the pH bouncing around. It is about 11 months old so I know the acid consumption may still be a little high, but I'm going through almost 4 gallons/month.

Thoughts???

Jim

 

[JasonLion]

Water to acid ratios between 3 to 1 and 5 to 1 should all be fine.

The main reason the acid is diluted in the tank is to avoid have lots of dangerous fumes every time you opened the tank. It also makes it simpler for the system to measure quantities, since those pumps are not really accurate at doing extremely small additions. The system does have some flexibility in the acid concentration, but large changes are likely to cause problems.

 

[Aquaman95]

The pump itself can handle full strength muriatic just fine. The fume issue as Jason pointed out may be the reasoning. It may also be because running the Stenner mechanical feed rate control on a lower setting will wear it out faster. It is preferable to dilute the acid or run a smaller feed tube size rather than turn down the feed rate control. I have no idea what size the feed tube is that ships with the Total Control but Stenner feed tubes are available in sizes 1 through 5 with 1 being the smallest diameter and lowest output. The tube size is inked on the tube and stamped in the plastic threaded connector at the end of the tube.

If you want to overcome the fuming issue you could use a product called "Acid Magic" instead of regular muriatic. It is the same strength as regular muriatic but has an additive that prevents most of the fuming. It is normally available at most Ace Hardware stores.

 

[Poolsean]

Jason nailed it.
You can increase the strength if you want. Also, as Aquaman said, the Stenner pump is capable of full strength acid too (however, we do not have a feed rate control and we use the #1 size tube). It's much safer to handle a diluted acid solution though.

On larger pools, such as yours, increasing the acid strength is a good idea to prevent frequent acid solution replenishment. My pool is 19,000 gallons and I use a 2.5 to 1 ration, rather than our recommended (in our manual) 4 to 1 ratio.

 

[Belldiver]

So explain to me what the difference in tube size makes? This pump seems to make the same speed/time cycle every time. Why would changing the tubing size do anything for me here?

I don't want to use more total solution. Actually, the opposite. If I just keep the tubing size the same, but increase the concentration to 1/3 or 1/2, that should do the trick right? I'm thinking that somewhere in that range should last in the 5 week range, which is more than enough for one of my work hitches.

On a side note...how often do I have to change that peristaltic tube?

Thanks for the input.

Jim

 

[JasonLion]

The special tube in the pump should be replaced every year, or perhaps every other year.

Using a larger feed tube allows more liquid to go through the pump for each revolution. You don't want to change that. The AutoPilot system is designed for a specific feed rate. It can handle some variation in the feed rate, but changing the tube size would be too large of a change. You can explore the entire range that the AutoPilot system can handle just by changing the water to acid ratio.

With the water to acid ratio at 3 to 1, you shouldn't have any problem at all going 5 weeks without refilling the 15 gallon acid tank. The only exception I can think of is if your TA level is too high. High TA levels can require a lot more acid. If your TA is above 90, you might want to think about lowering it.

If you post a full set of water test results, I can give you specific advice about what to adjust to be ideal for the Total Control system.

 

[Belldiver]

I'm still at work right now so I can't test the water this minute, but the following is what I shoot for at most times and am pretty good at keeping in this range. I do notice that I am constantly having to raise my TA. I usually bump it up to ~90 and over the course of a week it tends to drift down toward 70. I'm trying to keep it in the 90 range to help the CSI stay higher with the colder water over the winter.

pH 7.6
FC 3
CC 0
TA 70-90 usually varies in this range
CH 300
CYA 70
Salt 3300
Temp ~81 right now

When I let TA get down to 70 or below, it really lowers the CSI so I try to keep it nearer 90. Does this cause my acid consumption to go up? Which makes my TA drop? Are the acid and baking soda fighting each other somehow?

Thanks...

Jim

 

[Belldiver]

and FYI, I am using the Total control pH control system, but using the SC-60 cell manually.

 

[JasonLion]

Yes, trying to keep the TA high causes the system to feed more acid, which causes the TA to go back down.

Ignoring CSI for a moment, the normal recommended TA level for a SWG is between 60 and 80. You can actually let your TA go down as low as 50 without any problems (other than CSI). As the TA goes down the rate of acid feed will go down. To keep the PH regulation working you don't want the acid feed rate to go down too far. So if your PH starts to wander down, you should raise the TA just a little.

I suggest raising CH to 350 and letting TA go down to 60. That will lower your CSI a little, but that shouldn't be significant.

 

[Belldiver]

I'll try letting the TA stay a little lower and raising the CH some more. I guess letting the pH creep up to 7.7 won't hurt anything either and that well keep the CSI a little better until the water really warms up this summer. If I add borates this year, it appears it may aggravate the problem slightly too.

It doesn't appear that I can really keep CSI at or near zero in this situation without excessive acid/baking soda consumption? I'm not truly concerned with the cost of the chemicals, just the maintenance of the Stenner pump if it is always having to feed. I will likely change the feeder tube before it hits one year of service, just to be certain it doesn't fail while I'm offshore. Seems like cheap insurance to change out once/year. I will also try a 1/3 ratio on the acid.

Thanks again...

Jim

 

[JasonLion]

You don't really want to keep CSI at exactly zero. CSI is higher inside the SWG cell, where scaling is most likely to occur. It is also higher inside the heater. It is best to keep the CSI a little below zero, so it doesn't get too high in the cell or the heater.