Pbrown3701
New member
it's working fine so far. The pump heads are identical as are the motors. What makes you think it would be difficult?
DIY Dual Head Peristaltic Pump help
- Thread starter Pbrown3701
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Pbrown3701
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Good point.
I think Erikk is dosing trace elements though. For 2 part, if you slightly overdose, then it's not that big of a deal as the calcium and alk will simply precipitate out. As long as you're not drastically overdosing, you shouldn't see much impact - at least from my experiences.
I think Erikk is dosing trace elements though. For 2 part, if you slightly overdose, then it's not that big of a deal as the calcium and alk will simply precipitate out. As long as you're not drastically overdosing, you shouldn't see much impact - at least from my experiences.
Horace
New member
I dissagree here. If your dosing is not precise, your alk will steadily rise or fall. The idea is to get your dosing matched to exactly the consumption of the tank. If you are using a method which cannot be adjusted precisely, it will be very difficult to set this up so that it keeps your levels stable over time w/out constantly messing with it. Also, the Alk/Ca will NOT precipitate out unless you dump ALOT in at one time. If you slowly over time put too much in, the levels will just continue to rise off the charts. I have run 2 part with a very precise dosing pump, and even then it requires occasional adjustment to keep stable. I imagine with this setup you would need to test ALOT to ensure your levels either are not going through the roof, or dropping out. When my setup was tuned right, I could let it go for 2-3 weeks w/out the alk going up/down by more than about .5dkh. I find it highly unlikely you could do that with this setup.....
One other key thing to remember is (if your not doing this already), you MUST have the hoses enter the sump at opposite ends or as far apart as possible. If they are right next to each other it will create a high concentration of alk/ca near eachother which WILL cause it to precipitate out. Unfortunately this means that most of the 2-part you add will be wasted.....
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ok so if your doing this with a timer, why not just get a aqualifter?
Ive been planning to get a needle valve, and aqualifter and a digital timer to dose my stuff(just dont have the time) After a few tests to get the valve set right wouldnt it be basicly the same thing?
Ive been planning to get a needle valve, and aqualifter and a digital timer to dose my stuff(just dont have the time) After a few tests to get the valve set right wouldnt it be basicly the same thing?
Pbrown3701
New member
We can agree to disagree then. The solution of alkalinity and calcium follows standard solubility principles. They have a Ksp value above which, they will precipitate. I try to keep my tank at the maximum calcium levels possible and add alk part in balance. Thus, if i exceed my maximum calcium level, it simply precipitates out as calcium carbonate. My calcium level stays right at 435ppm and my alkalinity stays at 3.75meq. If i try to raise either anymore, it settles back down to these values. It is impossible for alkalinity to continue to increase as you claim - if both parts are added in balance.
I have both pumps outputs together in the sump, but run the timers for the pumps to come on 12 hours apart (alk in the early am to counter pH swing).
Pbrown3701
New member
Because it is extremely difficult to get exactly the same flowrate with two different diaphram pumps. Peristaltic pumps deliver a precise and known quantity for every revolution.
It doesnt matter if the two different diaphram pumps or peris are equal or not with two part. Most if not all tanks will be lopsided as to their ca and alk needs. You also cannot use a valve and an aqualifter with two part and expect it to dose the same from day to day. With the aqualifters the outlet needs to be wide open to get long term dosing.
Don
Don
Pbrown3701
New member
Don - good point about the valve on the diaphram pump. ALso, the head height of the fluid will change over time and also cause changes in dosage.
Regarding the 2 part however, i'm not sure your correct. THe process of calcification uses equal parts of alkalinity (carbonate) and calcium. Thus, all tanks (wether SPS, LPS, softies, fish only) should use the same amount of Alk and Cal. However all tanks will use differetn ammounts and testing until you get the appropriate dose. To do this, I started with a "guess" on the amount of each part and then tested each day with that guess. Then plotted the change in concentration. I then changed my "guess" and tested. I repeated this until test results from day to day were the same. On this same front, I also tried to increase the Calcium (was shooting for 450ppm) by upping the dose of both parts but found that for my tank, I could not exceed 435ppm and 3.75meg
Regarding the 2 part however, i'm not sure your correct. THe process of calcification uses equal parts of alkalinity (carbonate) and calcium. Thus, all tanks (wether SPS, LPS, softies, fish only) should use the same amount of Alk and Cal. However all tanks will use differetn ammounts and testing until you get the appropriate dose. To do this, I started with a "guess" on the amount of each part and then tested each day with that guess. Then plotted the change in concentration. I then changed my "guess" and tested. I repeated this until test results from day to day were the same. On this same front, I also tried to increase the Calcium (was shooting for 450ppm) by upping the dose of both parts but found that for my tank, I could not exceed 435ppm and 3.75meg
Nope that is not accurate at all. I can tell you from 20 years of sw and now 12 years of reefkeeping that its not the case. You have to take the entire system into account not just how corals calcify. Precip plays a big role and is a function of ph that you have very little if any control over.
Don
Horace
New member
Pbrown, I gotta tell ya, I have no idea where your observations are coming from. I have sent my alk MUCH higher, as well as my Ca by dosing too much per day. My dosing pump also was on 24/7, only dripping a very slow amount per hour. If I had my pump dialed up even slightly too high, it would send my Ca up over 500 and the Kh up very high too if not watched carfully. Your pretty much trying to tell us that you cant get your alk/ca out of whack if you dose equal parts, well i am here to tell you that you are absolutely incorrect, ive seen it MANY times in my own tank. Ive also seen this same thing occur with a CARX, which hopefully you know deliver EXACTLY 50/50 balance as the media desolves. If your theory was true, everyone could just set thier reactors to whatever level, as well as thier dosing pumps and everything would just fall in line. I only wish it were so easy!
Pbrown3701
New member
Horace - if you dose constantly, then yes, it is possible to dose faster than precipitation can occur and in that case, you will have higher readings. However, I guarantee if you stop dosing and leave that same tank alone for a few hours, those readings would drop back down to equilibrium. It's all chemistry my friend.
Horace
New member
Being a chemical engineer I would hope you would know a bit about this. However, I can tell you that just stopping the dosing is not going to cause the Alk/Ca to drop quickly by precip. It takes days to have the Alk/Ca drop, and that occurs mainly because of corals growth, NOT because of precipitation. If precipitation was the main source of the alk/ca drop, we would have tanks full of calcium carbonate at the rate we are injecting it into our systems. I think the only reason you are seeing any sort of precipitation is because your dosing it too fast and causing your PH to rise in the area your dosing, thus precip occurs. Your the first person I have heard that attributes any significant alk/ca usage to precip.
Pbrown3701
New member
Horace, I haven't see any precipitation since doing this DIY actually. However, if i dose too much of each part, then I definitely see precipitation in the form of frosted sump and heaters.
If you hold your tank at artificially elevated (supersaturated) levels of calcium and alkalinity hardness, then you will see precipitation. I don't mean precipitation in the form of a "snow storm" like some report - i mean frosting and hardening of the substrate.
Also, I never said or suggested that precipitation was the main source of alk/ca drop. However, if you run your levels up, it would quickly and easily become the fastest avenue for lowering the readings.
If you hold your tank at artificially elevated (supersaturated) levels of calcium and alkalinity hardness, then you will see precipitation. I don't mean precipitation in the form of a "snow storm" like some report - i mean frosting and hardening of the substrate.
Also, I never said or suggested that precipitation was the main source of alk/ca drop. However, if you run your levels up, it would quickly and easily become the fastest avenue for lowering the readings.
Pbrown3701
New member
Don - also, not to argue just for the sake of arguing, but precipitation occurs in a 1:1 ratio also, so alkalinity or calcium usage should be very close to the same. Of course in real life, it will be slightly different, but not different enough that one should dose different amounts IMO.
Pbrown3701
New member
Don, and also, lets not forget that there is a lot more calcium in our tanks than carbonate, so we notice alkalinity change more so than calcium - it changes by a larger percentage. However, both are used in the same ratio.
For every 20ppm ca you loose 2.8 dkh PLUS additional dkh due to normal bilogical process that have no need for for ca. We can also have additional loss of ca and mg to precip which we have no control over and is subject to change based on temp and ph. Would be nice if you could just grab two bottles of balanced two part and dose it in equal parts and have everything be peachy but it doesnt work out that way. There are to many other factors that we have no control over. Looks good on paper or a text book but isnt going to happen for long in a closed reef system.
Don
Don
Pbrown3701
New member
Well, it works fine in my system
Horace
New member
I will say that it does/did work just fine in my system as well. I very very rarely ever have to adjust one or the others independently. I agree they may not get used EXACTLY the same, but its very very close, and it takes several weeks if not several months for the imbalance to become an issue.
As for your supersaturation theory, yes, you are correct. But the levels your talking about hardly are super saturated. A level of 430ppm Ca is a far cry from super saturated. Ive run my Ca up over 500ppm and still not had any of the frosting you are talking about. The only time ive ever seen frosting is when I accidentally dosed a full gallon of each part in about 5 mins due to a siphon. This turned the tank pure white...the water was like milk. At that point there was major precip because of the high levels of saturation and sky high PH. If you have frosting, then you must be running your PH sky high.....I never even saw frosting when I had my PH at about 8.6 while dosing kalk.
As for your supersaturation theory, yes, you are correct. But the levels your talking about hardly are super saturated. A level of 430ppm Ca is a far cry from super saturated. Ive run my Ca up over 500ppm and still not had any of the frosting you are talking about. The only time ive ever seen frosting is when I accidentally dosed a full gallon of each part in about 5 mins due to a siphon. This turned the tank pure white...the water was like milk. At that point there was major precip because of the high levels of saturation and sky high PH. If you have frosting, then you must be running your PH sky high.....I never even saw frosting when I had my PH at about 8.6 while dosing kalk.
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