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post #1 of 10 (permalink) Old 04-01-2005, 12:19 AM Thread Starter
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vacation dosing

I didnt want to hijack anyones thread but I will be needing to figure something out by june for a 4 week vac. Im going to look for two peristalic pumps. I get it that one is for CSM +B but then are you saying you dilute KPo4, kNo3, K2so4 all together in water to use in another pump? If I use 1/2-1/4tsp kn03, 1/8 kno4, and 1/8 k2so4 every other day then how much of each would I mix up with how much water for say 15 days?

I got the formula for 1 TBSP csm+B to 250ml distilled water but how would it work for the others?

ernest

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post #2 of 10 (permalink) Old 04-01-2005, 05:22 AM Thread Starter
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Not only am I confused on how much to dilute macro ferts but how would I get the peristaltic pump to run every other day to step micro and macro dosing? Would I put them on 48hr timers or are the peristaltic pumps programmable?

ernest

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post #3 of 10 (permalink) Old 04-01-2005, 11:09 AM
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Thanks for starting a new thread. It's important that we get as much feedback on our plans for dosing prior to our vacations and the sooner the better. I've got all my equipment and just now worked out some calculations using Chuck Gadd's Calculator.

Limits
First you must come to the realization that you do not have to add your nutrients on alternate days. You can add them every day, just use half the amount on each day. You should have an idea of about how much your biomass consumes nutrients per day. This is done when you have fine-tuned the EI method to suit your plant's requirements. I'm finding that with my HQI MH pendants my plants are using/storing 13 ppm nitrates and 2 ppm phosphates every two days. I assume the plants are using/storing at least 13 ppm potassium and try to dose potassium accordingly. I've also found I can go two weeks without a water change while still maintaining my dosing regimen, even after moderate pruning, with no ill effects.

So now I look at my newly purchased equipment and find that the SP3000 Aquamedic peristaltic pump pumps at a constant rate of 50 ml/min. and the digital timer has a minimmum programmable time of 1 min. so, the minimum volume I can add per dose is 50 ml. These are the minimum limits of my equipment.

Macronutrients
How Many doses will I need? I will be gone 16 days and I want to be able to test it beforehand, so 16*50 ml = 800 ml. I'll make up 2000 ml so that I have enough to test/add for a week before I leave and some left over so my tubing stays submersed. I can use the remainder when I come back. Heck, if all goes well, I may even keep it an automated dosing system.

Using Chuck's Nutrient Calculator, I put in 2000 ml as the amount of water to mix with and entered my aquarium volume. I find that 130 g KNO3 gives a concentration of .12 ppm nitrate per ml for my 90 gallon tank. Multiplied by 50 ml I get 6 ppm per dose, which is close enough to the 6.5 ppm nitrates my biomass uses daily.

For KH2PO4 I find that 20 g in 2000L gives a concentration of 0.02 ppm phosphate per ml for my 90 gallon tank. For a 50 ml dose would give 1 ppm, which is what is used on a daily basis.

Finally Potassium. I find that I'm getting 3.5 ppm of K per dose of KNO3 (using Chuck's calculator), so I want to add another 3 ppm daily to match that of nitrate (roughly). The calculator doesn't calculate the potassium derived from KH2PO4, but I assume it is negligable as the target range for potassium is quite large. I found that 90 g of K2SO4 in 2000 ml of water gives 0.06 ppm per 1 ml for a 90 gallon tank. Multiplied by the 50 ml gives 3 ppm per dose. Add that with the potassium from KNO3 and I will get 6.5 ppm per 50 ml dose.

One thing you need to think about when figuring out your macronutrient stock solution is the solubility of each component. KNO3 dissolves quite easily as we all know. It has a solubility of 85 g per 100 ml of water. KH2PO4 and K2SO4 on the other hand have a very low solubility; only 15 g per 100 ml and 12 g per 100 ml of water. This comes into play if you were thinking about making a more concentrated stock solution.

Since I will be making up a dilute stock solution, I will only be adding 5.8 g KNO3 per 100 ml Water, 1 g KH2PO4 per 100 ml Water, and 4.5 g K2SO4 per 100 ml Water, so all components should dissolve nicely. I believe solubilities are additive, so that would give me 11.3 g per 100 ml of Water which is very close to the maximum solubility of 12 g per 100 ml Water for K2SO4. We'll see!

Micronutrients
Since I still have not heard of a good reason for not mixing micros with macros I'm planning on doing just that. If reactions/precipitates were going to happen, they would do so in the tank itself and we'd know about it by now, IMO. I find that I'm using 20 ml per day of my stock solution of 1T CSM+B in 250 ml Water which gives me 0.2 ppm Fe in my 90 gallon tank. Again, I've been doing this with no ill effects, just the opposite, I've noticed very positive effects in plant growth and overall plant health. So in order to continue to dose 0.2 ppm dialy, my stock solution must be multiplied by a factor of 2.5 (50/20) so that I will add 1T CSM+B in 625 ml Water. But that alone still won't give me 0.2 ppm per 50 ml dose from a 2000 ml macro/micro stock solution, so I multiply it by 3, so 3T CSM+B in 1875 ml Water (rounded to 2000 ml is close enough), will give approximately 0.2 ppm, per 50 ml dose.

Actually, I may not have enough solubility in my stock solution to also add the micronutrients and expect it all to be dissolved, so I may need a seperate dosing system anyway. I have a Kent's drip system, but that would require it to be "on" 24/7, which may not be efficient. Dang, I guess I need another perstaltic pump and only 14 days to vacation! That's why we need to think about these things way in advance.

Testing
I still need to find 1/4" OD tubing for the pump and test it to see if I actually get 50 ml in one minute and adjust my calculations as necessary. There is actual tubing inner diameter and height from pump to top of tank to consider and will affect the actual pump rate. I also want to test the aquarium water after the first automatic dose to see if I'm getting what I expected and I want to keep testing regularly to see if the plants are using/storing nitrates and phosphates at expected rates.

All in all there's only so much that can be planned for. My area is notorious for power outages while I'm on vacation, but since all my equipment, including feeder is electrical, they should all be in synch when the lights back come on....unless the digital timer resets itself then the fertilization time may be off which isn't bad...I'll have to check!
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post #4 of 10 (permalink) Old 04-01-2005, 11:26 AM
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In vacantion I cut the dosing (also Aquemedic 3000 pumps) by half and more important : I lower the light intensity and duration.
8 hours max a day.
The growth is slowed down, but so are problems.
Also check your CO2.....
Fish are fed by the neighbour : very little. I make feeding portions ready in advance and she can give the fish every other day one portion.

Gr. PJAN
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post #5 of 10 (permalink) Old 04-01-2005, 11:39 AM
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Quote:
Originally Posted by Gill Man
Since I still have not heard of a good reason for not mixing micros with macros I'm planning on doing just that. If reactions/precipitates were going to happen, they would do so in the tank itself and we'd know about it by now, IMO.
Gill Man, don't mean to rain on your parade, but you are not looking at all the possibilities. If they precipitated in the tank, one would hope we would know about it by now. So let's assume they don't for the moment. That leaves us two possibilities about mixing micros/macros in more concentrated solutions:

1) Stories about precipitates are untrue. Well you can test that yourself. Mix 'em up in a glass that you can see through, wait a few minutes and see what you find!

- or -

2) The stories ARE true, but for some reason it doesn't matter once they get mixed in the tank.

IMO it must be number two above, and I assume that has something to do with concentrations. I'm no chemist, but I do know what I can see with my unaided eyes when you mix an iron containing fert solution (TMG or Seachem Iron) with a strong P or K solution.

If you want to ignore it easily verifiable evidence, go right ahead. The only thing that will suffer is your plants.

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #6 of 10 (permalink) Old 04-01-2005, 11:56 AM
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It appears that the Grasslin Digital Programmable Timer can be programmed for certain days of the week so you can still maintain an alternate day dosing regimen. It also has an internal battery so it will maintain the set time and it's programmed settings after a power outage, which makes me think that perhaps I should use get one for my lighting as well, instead of the old mechanical one. How 'bout one for the moonlights? They can be programmed in the on or off position. The technical data states the Voltage: 120V and the Switching Capacity: Resistive: 15A/125VAC and Output is 1 SPST (dunno). I'm wondering if the it can hande the total voltage of my 2x150W MH lights? Should I get one for each pendant? I'm looking at 4 more timers at $20 ea. from Dr. F&S. plus another SP3000 pump. Oh, well, it's only money...well credit any way.
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post #7 of 10 (permalink) Old 04-01-2005, 12:06 PM
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Ernest - there are alternatives to the high volume Aquamedic dosers. Some peristalic pumps will pump very low doses, for much better control over lower volumes. You might want to take a look at this thread.

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #8 of 10 (permalink) Old 04-01-2005, 12:10 PM
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Re: Mixing macro and micro nutrients:

The only likely (as I see it) precipitates on mixing them together:

Fe3(PO4)2*8H2O: Iron(II) and phosphate - Ksp = 1*10^-36
Zn3(PO4)2*4H2O: Zinc(II) and phosphate - Ksp = 5*10^-36

Even though the iron is complexed in micro mixtures, that complex does not look to be strong enough to prevent displacement by phosphate. This does not really apply to the aquarium since both Fe and phosphate are at such low concentrations by then.

All nitrate salts are soluble, so you can mix the nitrate in with the micros. Potassium salts are all soluble as well, and only a few sulfate salts are insoluble (Ca, Sr, Ba, Ag, Hg, Pb), so the K2SO4 should be fine (as long as it dissolves initially - 1g/8.3ml).

Mix it all up and see - if the concentrations in your dosing solution are low enough, it might still work.

Kevin

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post #9 of 10 (permalink) Old 04-01-2005, 12:12 PM
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Steve, it does sound like it is easily verifiable. I've just never added iron ferts to strong concentrations of K or P in a glass of water before, but I trust your observations and it's the first I've heard of it, so thanks.

As I went on to say, I don't think I can get anything else to dissolve in the stock solution given the low solubilities of K2SO4 and KH2PO4, so I will indeed need a separate dosing pump for my micronutrient mix.

I'm now trying to figure out what the maximum load capacity (watts) I can carry on each digital timer. The SP3000 pumps have a power consumption of 4.5 watts, which doesn't sound like that much so I can probably use one timer for two pumps, but can I use a single timer for 300 watts? I guess since I'm using the regular timer with 300 watts it's OK, but I wonder if it's safe?
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post #10 of 10 (permalink) Old 04-07-2005, 12:08 AM Thread Starter
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Thanks everyone for spending the time to lay it all out and Gill Man please post how things go when you get back. Im curious to see if you decide to keep the pumps running as a automated dosing setup.

I have convinced a friend to house sit for us. Save the money I would have spent on automating ferts and pay him to watch all our animals. I still dont want to have him do weekly W/C's so I am using some of your advise by cutting back doses and lower lighting down to 8hr a day. Trim the plants back hard and a large W/c before we leave. Hopefully I wont come back to a tank full of algae but I feel much more at ease this way rather than having equipment running that could fail. Feel free to post any more precautions you can think of.

thanks

ernest

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