Rex Grigg Manifold Question - The Planted Tank Forum
 
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post #1 of 7 (permalink) Old 04-06-2018, 06:58 PM Thread Starter
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Rex Grigg Manifold Question

Have a 2 fold question.

I have a 125g densely planted tank.
Using Rex Grigg regulator which I bought maybe 10 years back.

Seeing lots of algae and am thinking the most of the plants on the other side of the tank are not getting enough CO2. The CO2 diffuser outlet bubbles feed into canister filter inlet. Have a powerful powerhead too.


Thinking about installing 2nd diffuser on the other side of the tank.
Is this a good idea and will it help with the co2 dispersion on the opposite side of the tank?

If installing a 2nd diffuser what kind (any recommendations) of manifold should I get for the Rex Grigg regulator? Is the manifold easy to install?
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post #2 of 7 (permalink) Old 04-06-2018, 07:17 PM
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This is funny, I was just looking into this the other day. Here's some stuff on making a manifold -
https://www.plantedtank.net/forums/9-...regulator.html

What type of algae are you seeing? I might look at light and fertilizers before CO2.
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post #3 of 7 (permalink) Old 04-07-2018, 04:01 AM
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Manifold is one of those "high tech" sounding ters which means very little as it is really only something to add a second path. For two tanks or two reactors, a tee can serve as a "manifold" but most would want to add a second needle valve to allow for setting how much flows through each reactor. As easy to set up as cutting the existing tubing in any location, adding the tee and second needle valve . It does work somewhat like house plumbing in that when one is opened more the other will get less and may also need to be set a bit wider. Simple but requires some "fiddle" time?
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post #4 of 7 (permalink) Old 04-07-2018, 12:23 PM Thread Starter
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Quote:
Originally Posted by mgeorges View Post
This is funny, I was just looking into this the other day. Here's some stuff on making a manifold -
https://www.plantedtank.net/forums/9-...regulator.html

What type of algae are you seeing? I might look at light and fertilizers before CO2.
Thanks for the link.
This looks like it'll work but with the limited and average reviews I am a little apprehensive.
https://www.amazon.com/dp/B01F8KA89Y...vert-amazon-20

Anyone who has a Rex and installed a manifold give a recommendation please?


Seeing quite a bit of BBA.
I looked into lights and Ferts too - but this seemed the easiest to start with.
7 Hrs lights and EI dosing every other day.
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post #5 of 7 (permalink) Old 04-07-2018, 04:52 PM
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I would not recommend that unit due to the way it is made. Some understanding of what makes a good needle valve may help.
We use a really, really, tiny amount of CO2 and that makes it very important that we be able to move the adjustment on the needle valve and get terribly small change in the opening. Two things make that possible. One is that the needle needs to be long and have a very sharp taper. Think of a sewing needle versus a screw, perhaps. One is long and finely tapered and as it is moved into a precision hole, the opening changes very little but with the screw, moving the same distance forward gets a much larger change due to it being much more blunt. So a long thin needle is better.
The second part is the threads inside the valve which move the needle forward or back. More threads per inch means the needle moves less for each turn of the adjustment. The better valves take many turns (maybe 32?) to move from closed to fully open. The cheaper ones may move fully in four turns of the adjustment. One that we can turn a tiny bit to move the needle forward a really tiny bit is better than one which jumps forward every time we even touch the adjustment.
The problem is that good metal that allows fine machining is not cheap and the pot metal many cheap ones use is just not a workable item for precision.
Short, cheap, valves of cheap metal will just often be "cheap".
How cheap and how much we are willing to put up with is always a personal choice but many find they wish for better.
I use the Fabco NV-55 line as a "middle of the road" valve.
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post #6 of 7 (permalink) Old 04-07-2018, 05:31 PM
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Rather than complicating your CO2 system, why not just improve the flow pattern in your tank? You're injecting the same amount of CO2 onto the same volume of water, so if you think it is CO2, improving the flow (or path of flow) would be an easier way to test that theory.

BBA is often too much organics in the tank. We've had people people pushing 45ppm of CO2 with no reduction in BBA, and you'll even see BBA growing on the outflow from the canister where CO2 should be at its highest concentration in the whole tank.
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post #7 of 7 (permalink) Old 04-09-2018, 05:27 PM Thread Starter
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Thanks all for your suggestions.
It's a big tank and circulation is a challenge.
Will add a 2nd powerhead on the other side and see if it makes a difference.

Any powerhead recommendations?
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