EI Dosing with a trickle water change system

Wookii

Member
Joined
13 Nov 2019
Messages
975
Location
Nottingham
Hi guys,

I'm coming back to planted aquaria after 16 years off. Whilst keeping a planted tank, and CO2 operation isn't overly new to me, EI dosing is - but it is a system I want to have a go with.

I'm planning to use EI dosing on a 70 litre tank, via a Jebao doser.

The tank will be set up with a 20 litre header tank with solenoids for fully automated water changes. This will allow me to do 20% water changes up to a realistic maximum of probably once per day. Initially however I intend to do a water change once every three days:

Day 1: First solenoid opens and tank fills with water, comes to temperature, and mixes properly over 24 hours with dosed stress coat (circulated by airstone) to remove the tap water nasties
Day 2/3: Second solenoid opens to release treated water to the tank as a trickle over 24 or 48 hours (to be decided).
Day:4+: Repeat . . .

On reading all the guidance on EI dosing however, the assumption is a complete instant water change of 20-50% in one go.

My questions are:

1. Is 20% every three days sufficient given the way the dilution will occur (i.e. 2 x 20% water changes over 6 days on a trickle system not producing the same dilution as a single static 50% weekly water change)?

2. Likewise, how will using a trickle water change affect how much I should dose? - I appreciate the EI dosing is not rigid, and based on there simply being excess nutrients, but do we need to avoid those nutrients building up to higher levels over the longer term by getting the wiring balance between water changes and dosing?

Thanks in advance for any advice.
 

dw1305

Expert
Joined
7 Apr 2008
Messages
10,941
Location
nr Bath
Hi all,
Is there a good quality model you can recommend?
Most low range meter (0 - 1999 (or 3999) microS) will do. Ideally I wouldn't go cheaper than about ~£50 and "automatic temperature compensation (ATC)" is useful, but not essential.

They are much lower maintenance bits of kit compared to pH meters, and you can make up the <"calibration solutions">. You may be able to find a second hand "Hanna" one on Ebay etc.
Is there a way of establishing an ideal target TDS, based on the tap water TDS as a starting point?
Yes. Start by measuring the tap water. It could be anywhere between approx. 50 microS and 800 microS, dependent on how hard the ground water source is. This doesn't matter, it just gives you an intial <"datum range">.

If the water comes from a <"deep aquifer"> the conductivity value should be consistent through-out the year, if it has a surface water component (look at @AverageWhiteBloke's comments in <"........popping kettles"> ) the value will be lower in the winter and higher in the summer.

Add your EI salts to your tank water, wait ten minutes and measure the conductivity again (turn off everything that is electric in the tank while you take the reading), this is your second datum value. After you've done your weekly water change follow the same procedure, this is your third value. Do this for a couple of weeks until you have a range of values. Carry on a for a couple of weeks with your normal fertiliser, and water change regime, assuming you are happy with plant growth you should be fine, but you can take another set of measurements, if your second and third datum values have risen noticeably you need to change a larger volume of water.

cheers Darrel
 

Wookii

Member
Joined
13 Nov 2019
Messages
975
Location
Nottingham
Hi all,Most low range meter (0 - 1999 (or 3999) microS) will do. Ideally I wouldn't go cheaper than about ~£50 and "automatic temperature compensation (ATC)" is useful, but not essential.

They are much lower maintenance bits of kit compared to pH meters, and you can make up the <"calibration solutions">. You may be able to find a second hand "Hanna" one on Ebay etc. Yes. Start by measuring the tap water. It could be anywhere between approx. 50 microS and 800 microS, dependent on how hard the ground water source is. This doesn't matter, it just gives you an intial <"datum range">.

If the water comes from a <"deep aquifer"> the conductivity value should be consistent through-out the year, if it has a surface water component (look at @AverageWhiteBloke's comments in <"........popping kettles"> ) the value will be lower in the winter and higher in the summer.

Add your EI salts to your tank water, wait ten minutes and measure the conductivity again (turn off everything that is electric in the tank while you take the reading), this is your second datum value. After you've done your weekly water change follow the same procedure, this is your third value. Do this for a couple of weeks until you have a range of values. Carry on a for a couple of weeks with your normal fertiliser, and water change regime, assuming you are happy with plant growth you should be fine, but you can take another set of measurements, if your second and third datum values have risen noticeably you need to change a larger volume of water.

cheers Darrel

Thats great thanks Darrel.

I've had a quick look, and struggled to find many with a an operating range of 0-1999ppm (most seem to be 0-9990ppm). Found this one on Amazon though, will this be okay do you think:

https://www.amazon.co.uk/Hakeeta-Co...43?keywords=TDS+0-1999&qid=1573824114&sr=8-43
 

akwarium

Member
Joined
20 Feb 2010
Messages
187
Location
Haskerhorne, Netherlands
why not ad the nutrients in a 1:1 ratio with the fresh water?

so if you change 14 liters of water, you add nutrients to bring those 14 liters up to standard EI-levels. (or double in extreme high tech)
0 change of overdosing or nutrient build up.
 

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