# Ei with constant Drip Water change



## scans (Feb 3, 2006)

Well here is my first post....
I have a nicely planted 240 Discus tank with almost 600w of light and preasurized C02. I am currently doing the EI thing with the following levels:

micros
in 1/2 liter of water:
1 tablespoon of Plantex CSM+B
1 tablespoon of Magnesium Sulfate.
Add 75ml of solution every other day

Macros:
Mono Potassium Phosphate (KH2PO4) - 3/4 teaspoon and
Potassium Nitrate (KNO3) 1 tablespoon every other day.

My question is in relation to water changes. I have a constant drip water change in place that does 3-5 gph. Will this affect the dosing requirements? if so, how?

Thanks


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## fish7days (Jul 30, 2005)

You may want to ask guaic boy for his opinion on this too. Here is his response to my question on something related. I have seen similar questions and seem to recall that the answer was usually not to do constant changing, but rather to do it as a single event (under correction).

http://www.aquaticplantcentral.com/forumapc/equipment/12443-opinions-plse-auto-water-changing-calcs.html?highlight=automatic+water+changer


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## BryceM (Nov 6, 2005)

Scans, the drip method is perfectly acceptable and very easy. The only trick is keeping the inflow at a constant rate. This is pretty hard to do without some specialized flow monitoring equipment.

If you could set it up so that 50% of the water was changed each week by the drip method, you'd never have to do a formal WC - appealing huh?

Using a modification of the formula in the other post, I figured out that if you changed 0.99 gallons/hour in a 240 gallon tank that you'll acheive an effective 50% change per week. If you assume a 200 gallon water column, the answer becomes 0.82 gallons/hour.

If you drip in 3 gallons/hour you're doing a 92% WC per week (92% of the nutrients you put in will go down the drain if you assume no uptake from the plants). If you drip in 5 gallons/hour you're doing a 98.5% WC per week.

You either need to reduce the drip rate flow or drastically increase your fert dosing to compensate. In general, the math of theoretical nutrient levels is much, much easier to figure out if you just do a batch change once / week.


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## scans (Feb 3, 2006)

I know the once a week changes would be easier to calc dosing, but the Discus and my schedule LOVE the automated WC system. I'll have to figure something out. Maybe an auto doser?

I hope Tom Barr jumps on this (HINT)


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## scans (Feb 3, 2006)

If you are interested I had a big discussion about the WC system over on Simply:

Here is the link


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