Gate valve question!

[Alatuf]

Hi everyone! I have a question about gate valve. I imported and installed one from China into my drain. Here in Brazil we don't have them all in plastic! After I installed it I can see some minimal flow changes without touching the valve! It seems that it is "closing" a little bit. Because I can see through my Apex a salinity drop.
As I am new to this valves I would ask if someone has noticed this issue! And if there is anything to do to correct this!
I attached a picture of the valve! Please, just close your eyes for my sump mess! Lol

 

[Memisis]

Do you have an emergency return? I have a gate on my main return and a wide open emergency. Depending on how high the water is over the main will put more pressure on the valve and just a slight bit more will flow.

Another theory is that you have the valve close to closed stuff is getting stuck in there. Does your emergency overflow flow increase as this one slows? Does it speed back up after fully opening and closing again? Does anything pass through it when you do this? Lol lots of questions sorry.

Best of luck.

 

[Timfish]

Persaonally I would not put a valve on the drain line unless there is a backup or emergency drain line big enough to handle all the flow from the pump. The restriction caused by a valve promotes the build up and trapping of dtritus and small organisms which will slow down the flow. One thing you can do to troublwshoot is open the valve wide open then return it to it's original position to see if anything is flushed out.

 

[Gtinnel]

How are you using a salinity probe to determine reduced flow? As mentioned do you only have the one drain line, if so why have a gate valve on it at all?

Also, your sump is much, much neater than mine is.

 

[Alatuf]

Hi guys! First of all I would like to thank you for all help until now! As I live in Brazil I don't know all the terms you use in reef tanks! Sorry for that! But I will try to explain how my system is. I have an overflow box and a pipe where gate valve is installed. I think it is not a drain as I mention before. When the flow from this pipe is reduced my sump level decreases and RO water enters in the system and salinity drops.
I have already tried to open the valve to see if something was flushed out, but that was not the case. And when I close it to the same position, my sump level does not become where it was. It is increased. So, it seems that this valve is not precise! I do not know if I could make myself clear!
Before this valve I had a ball valve and never had any issue like this. But ball valves are terrible to make little adjusts.